Your post is interesting because we were recently reported a bug in SF where the engine is unable to mate in a KRK position, we think this could be due to some subtle interaction between 50 moves rule and TT because if you cold start the engine and set it on any of the troubled positions SF immediately finds the correct continuation.
[Event "DFT8"]
[Site "?"]
[Date "2011.09.06"]
[Round "1"]
[White "Stockfish 2.1.1 JA 64bit"]
[Black "Houdini 1.5a x64"]
[Result "1/2-1/2"]
[ECO "A14"]
[Annotator "-0.12;-0.04"]
[PlyCount "253"]
[EventDate "2011.09.06"]
[EventType "tourn"]
[TimeControl "2400"]
{Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz 3519 MHz W=19.7 plies; 10,021kN/s;
DFritz12.ctg B=23.5 plies; 16,235kN/s; 337,862 TBAs; DFritz12.ctg} 1. Nf3 {
[%eval 0,0] [%emt 0:00:00]} d5 {[%eval 0,0] [%emt 0:00:00]} 2. c4 {[%eval 0,0]
[%emt 0:00:00]} e6 {[%eval 0,0] [%emt 0:00:00]} 3. b3 {[%eval 0,0] [%emt 0:00:
00]} Nf6 {[%eval 0,0] [%emt 0:00:00]} 4. g3 {[%eval 0,0] [%emt 0:00:00]} c5 {
[%eval 0,0] [%emt 0:00:00]} 5. Bg2 {[%eval 0,0] [%emt 0:00:00]} Nc6 {[%eval 0,
0] [%emt 0:00:00]} 6. O-O {[%eval 0,0] [%emt 0:00:00]} Be7 {[%eval 0,0] [%emt
0:00:00]} 7. Bb2 {[%eval 0,0] [%emt 0:00:00]} O-O {[%eval 0,0] [%emt 0:00:00]}
8. e3 {[%eval 0,0] [%emt 0:00:00]} b6 {[%eval 0,0] [%emt 0:00:00]} 9. Nc3 {
[%eval 0,0] [%emt 0:00:00]} dxc4 {[%eval 0,0] [%emt 0:00:00]} 10. bxc4 {[%eval
0,0] [%emt 0:00:00]} Bb7 {[%eval 0,0] [%emt 0:00:00]} 11. Qe2 {[%eval -12,27]
[%emt 0:00:56]} Qc7 {[%eval -4,23] [%emt 0:00:58]} 12. d3 {[%eval 0,26] [%emt
0:00:42] (Rab1)} Rad8 {[%eval -3,23] [%emt 0:01:14] (a6)} 13. Rfd1 {[%eval 0,
29] [%emt 0:00:55] (Rab1)} h6 {[%eval 0,22] [%emt 0:01:07] (Na5)} 14. Ne1 {
[%eval 16,27] [%emt 0:00:53] (Rab1)} Na5 {[%eval -8,21] [%emt 0:00:33] (Ne8)}
15. f4 {[%eval 20,27] [%emt 0:01:13] (Nb5)} Bxg2 {[%eval -8,22] [%emt 0:00:39]
(Rb8)} 16. Kxg2 {[%eval 12,29] [%emt 0:01:46] (Qxg2)} a6 {[%eval -11,24] [%emt
0:00:40] (Qb7+)} 17. Nf3 {[%eval 28,28] [%emt 0:00:57]} Rb8 {[%eval -11,23]
[%emt 0:00:40]} 18. Nb1 {[%eval 16,27] [%emt 0:00:38]} Nd7 {[%eval -9,22]
[%emt 0:00:50] (b5)} 19. Nbd2 {[%eval 20,25] [%emt 0:00:41]} b5 {[%eval -8,21]
[%emt 0:00:57]} 20. Rab1 {[%eval 20,25] [%emt 0:01:11]} Rfd8 {[%eval -11,21]
[%emt 0:00:45]} 21. h3 {[%eval 24,25] [%emt 0:02:44] (a3)} Nc6 {[%eval -17,20]
[%emt 0:00:35]} 22. Rdc1 {[%eval 24,26] [%emt 0:01:49] (Ne4)} b4 {[%eval -23,
20] [%emt 0:00:28] (Qb7)} 23. Ne4 {[%eval 16,24] [%emt 0:01:22] (d4)} Rbc8 {
[%eval -22,20] [%emt 0:00:37]} 24. Rf1 {[%eval 16,25] [%emt 0:00:49] (g4)} f5 {
[%eval -19,21] [%emt 0:00:33] (Nb6)} 25. Ned2 {[%eval 0,26] [%emt 0:00:39]
(Nf2)} Nb6 {[%eval -16,20] [%emt 0:00:26] (a5)} 26. Nb3 {[%eval 16,25] [%emt 0:
00:52] (Ba1)} a5 {[%eval -6,21] [%emt 0:01:20]} 27. e4 {[%eval 8,27] [%emt 0:
00:30] (d4)} Qd7 {[%eval -31,22] [%emt 0:00:40] (Bf8)} 28. Rbd1 {[%eval 0,28]
[%emt 0:00:37]} Na4 {[%eval -23,23] [%emt 0:00:46]} 29. Ba1 {[%eval 0,28]
[%emt 0:00:47]} Nc3 {[%eval -23,23] [%emt 0:00:24]} 30. Bxc3 {[%eval -16,30]
[%emt 0:00:34]} bxc3 {[%eval -24,22] [%emt 0:00:00]} 31. Qc2 {[%eval -24,30]
[%emt 0:00:31]} a4 {[%eval -21,22] [%emt 0:00:23]} 32. Nc1 {[%eval 0,30] [%emt
0:00:51]} Rb8 {[%eval -24,22] [%emt 0:00:23] (Nd4)} 33. Qxc3 {[%eval 0,31]
[%emt 0:00:47]} Nd4 {[%eval -33,23] [%emt 0:00:32]} 34. Nxd4 {[%eval -28,31]
[%emt 0:01:56]} cxd4 {[%eval -33,23] [%emt 0:00:36]} 35. Qe1 {[%eval -36,25]
[%emt 0:00:25]} Rb2+ {[%eval -28,23] [%emt 0:00:34] (Rb1)} 36. Rf2 {[%eval -36,
27] [%emt 0:00:29]} Rdb8 {[%eval -51,23] [%emt 0:00:28]} 37. exf5 {[%eval -28,
28] [%emt 0:00:23]} exf5 {[%eval -48,24] [%emt 0:00:25]} 38. Qe5 {[%eval -66,
29] [%emt 0:01:39]} Ba3 {[%eval -47,25] [%emt 0:00:45] (Qc6+)} 39. Rxb2 {
[%eval -32,30] [%emt 0:00:37]} Rxb2+ {[%eval -46,26] [%emt 0:00:22]} 40. Ne2 {
[%eval -20,31] [%emt 0:00:34]} Be7 {[%eval -38,25] [%emt 0:01:16]} 41. Kf3 {
[%eval 0,30] [%emt 0:00:52]} Bf6 {[%eval -42,26] [%emt 0:00:19]} 42. Qd5+ {
[%eval 0,31] [%emt 0:00:22]} Qxd5+ {[%eval -42,25] [%emt 0:00:00]} 43. cxd5 {
[%eval 0,27] [%emt 0:00:01]} Rxa2 {[%eval -20,27] [%emt 0:02:00]} 44. g4 {
[%eval 0,32] [%emt 0:00:18]} fxg4+ {[%eval -21,27] [%emt 0:01:04]} 45. hxg4 {
[%eval 0,30] [%emt 0:00:19]} Kf7 {[%eval -21,26] [%emt 0:00:53] (a3)} 46. Ng3 {
[%eval 0,31] [%emt 0:00:18]} a3 {[%eval -15,26] [%emt 0:00:46]} 47. Ne4 {
[%eval 0,30] [%emt 0:00:17]} Rc2 {[%eval -17,26] [%emt 0:00:15] (Ke7)} 48. Rb1
{[%eval 4,29] [%emt 0:00:15] (Nxf6)} a2 {[%eval 3,23] [%emt 0:00:15] (Rb2)} 49.
Rb7+ {[%eval 56,29] [%emt 0:00:16]} Be7 {[%eval 3,26] [%emt 0:00:17] (Kf8)} 50.
Ra7 {[%eval 96,31] [%emt 0:00:18]} Kf8 {[%eval 3,26] [%emt 0:00:20]} 51. d6 {
[%eval 96,32] [%emt 0:00:18] (Ra8+)} Bd8 {[%eval 6,24] [%emt 0:00:13]} 52. g5 {
[%eval 60,32] [%emt 0:00:28]} hxg5 {[%eval 11,25] [%emt 0:00:19]} 53. Nxg5 {
[%eval 80,34] [%emt 0:00:12]} Bxg5 {[%eval 10,24] [%emt 0:00:00]} 54. fxg5 {
[%eval 80,37] [%emt 0:00:12]} Ke8 {[%eval 9,30] [%emt 0:00:12]} 55. Ke4 {
[%eval 52,35] [%emt 0:00:13]} Kd8 {[%eval 9,31] [%emt 0:00:12] (Rg2)} 56. Kxd4
{[%eval 52,37] [%emt 0:00:14] (Ra8+)} Rb2 {[%eval 9,30] [%emt 0:00:15] (Re2)}
57. Ke5 {[%eval 707,32] [%emt 0:00:13] (Kd5)} Re2+ {[%eval 130,30] [%emt 0:02:
07] (Ke8)} 58. Kf5 {[%eval 722,36] [%emt 0:00:10] (Kd5)} Kc8 {[%eval 248,21]
[%emt 0:00:22] (Ke8)} 59. d7+ {[%eval 1352,35] [%emt 0:00:43]} Kd8 {[%eval 248,
20] [%emt 0:00:00]} 60. Kg6 {[%eval 1551,31] [%emt 0:00:13]} Re5 {[%eval 303,
24] [%emt 0:01:42]} 61. Rxa2 {[%eval 7708,32] [%emt 0:00:14]} Kxd7 {[%eval 403,
23] [%emt 0:01:24] (Rd5)} 62. Ra7+ {[%eval 8277,36] [%emt 0:00:09]} Kc6 {
[%eval 422,22] [%emt 0:00:54] (Ke6)} 63. Rxg7 {[%eval 8298,37] [%emt 0:00:12]}
Re1 {[%eval 432,21] [%emt 0:00:06] (Rd5)} 64. Ra7 {[%eval 11865,37] [%emt 0:00:
09]} Rb1 {[%eval 455,20] [%emt 0:00:09] (Rg1)} 65. Kg7 {[%eval 9696,30] [%emt
0:00:07] (d4)} Kd6 {[%eval 561,20] [%emt 0:00:14]} 66. g6 {[%eval 11796,29]
[%emt 0:00:11]} Rf1 {[%eval 1156,23] [%emt 0:00:57] (Ke6)} 67. Kh7 {[%eval
11897,32] [%emt 0:00:28] (Rb7)} Kc5 {[%eval 1521,22] [%emt 0:00:47] (Rh1+)} 68.
g7 {[%eval 8924,24] [%emt 0:00:09]} Rh1+ {[%eval 1537,20] [%emt 0:00:10]} 69.
Kg6 {[%eval 32676,23] [%emt 0:00:24]} Kb6 {[%eval 1643,21] [%emt 0:00:07]
(Rg1+)} 70. Re7 {[%eval 32678,23] [%emt 0:00:02] (g8Q)} Rg1+ {[%eval 32728,21]
[%emt 0:00:09]} 71. Kh7 {[%eval 32672,14] [%emt 0:00:00] (Kf7)} Rh1+ {[%eval
32708,20] [%emt 0:00:04]} 72. Kg8 {[%eval 11845,24] [%emt 0:00:00]} Rh3 {
[%eval 32728,22] [%emt 0:00:03] (Rf1)} 73. Kf8 {[%eval 32686,16] [%emt 0:00:00]
(Rf7)} Rf3+ {[%eval 32728,30] [%emt 0:00:16]} 74. Rf7 {[%eval 32688,16] [%emt
0:00:00] (Ke8)} Rxd3 {[%eval 32734,35] [%emt 0:00:03] (Rg3)} 75. g8=Q {[%eval
32686,10] [%emt 0:00:00]} Rd8+ {[%eval 32734,1] [%emt 0:00:00]} 76. Kg7 {
[%eval 32688,10] [%emt 0:00:00]} Rxg8+ {[%eval 32736,1] [%emt 0:00:00]} 77.
Kxg8 {[%eval 32690,8] [%emt 0:00:00]} Kc5 {[%eval 32738,1] [%emt 0:00:00] (Ka6)
} 78. Rg7 {[%eval 32696,5] [%emt 0:00:00]} Kd4 {[%eval 32738,1] [%emt 0:00:00]
(Kb6)} 79. Rg3 {[%eval 32696,10] [%emt 0:00:00] (Rg4+)} Ke5 {[%eval 32738,1]
[%emt 0:00:00] (Ke4)} 80. Rd3 {[%eval 32724,5] [%emt 0:00:00]} Kf4 {[%eval
32738,1] [%emt 0:00:00] (Kf6)} 81. Kf7 {[%eval 32730,5] [%emt 0:00:00]} Ke4 {
[%eval 32740,1] [%emt 0:00:00]} 82. Rd7 {[%eval 32732,6] [%emt 0:00:00]} Ke5 {
[%eval 32742,1] [%emt 0:00:00]} 83. Ke7 {[%eval 32734,5] [%emt 0:00:00]} Kf5 {
[%eval 32742,1] [%emt 0:00:00]} 84. Kf7 {[%eval 32732,5] [%emt 0:00:00]} Ke5 {
[%eval 0,1] [%emt 0:00:00]} 85. Ke8 {[%eval 32726,5] [%emt 0:00:00]} Ke4 {
[%eval 32740,1] [%emt 0:00:00] (Ke6)} 86. Rd6 {[%eval 32712,8] [%emt 0:00:00]
(Re7+)} Kf5 {[%eval 32740,1] [%emt 0:00:00] (Ke3)} 87. Rd4 {[%eval 32724,5]
[%emt 0:00:00] (Ke7)} Ke6 {[%eval 32740,1] [%emt 0:00:00] (Ke5)} 88. Rd3 {
[%eval 32728,5] [%emt 0:00:00]} Ke5 {[%eval 32738,1] [%emt 0:00:00] (Kf6)} 89.
Kf8 {[%eval 32726,5] [%emt 0:00:00]} Ke4 {[%eval 32738,1] [%emt 0:00:00] (Ke6)}
90. Ra3 {[%eval 32698,10] [%emt 0:00:00]} Kf4 {[%eval 32740,1] [%emt 0:00:00]
(Kd5)} 91. Kf7 {[%eval 32702,9] [%emt 0:00:00]} Ke5 {[%eval 32740,1] [%emt 0:
00:00] (Ke4)} 92. Ra4 {[%eval 32706,6] [%emt 0:00:00]} Kf5 {[%eval 32742,1]
[%emt 0:00:00] (Kd5)} 93. Rd4 {[%eval 32732,5] [%emt 0:00:00]} Ke5 {[%eval
32742,1] [%emt 0:00:00]} 94. Rg4 {[%eval 32708,5] [%emt 0:00:00]} Kf5 {[%eval
32742,1] [%emt 0:00:00] (Kd5)} 95. Rg3 {[%eval 32702,5] [%emt 0:00:00]} Kf4 {
[%eval 32740,1] [%emt 0:00:00] (Ke4)} 96. Rb3 {[%eval 32702,8] [%emt 0:00:00]}
Ke4 {[%eval 32740,1] [%emt 0:00:00]} 97. Rb4+ {[%eval 32704,8] [%emt 0:00:00]}
Ke5 {[%eval 32740,1] [%emt 0:00:00] (Kd5)} 98. Rh4 {[%eval 32704,6] [%emt 0:00:
00]} Kf5 {[%eval 32740,1] [%emt 0:00:00] (Kd5)} 99. Ra4 {[%eval 32708,5] [%emt
0:00:00]} Ke5 {[%eval 32742,1] [%emt 0:00:00]} 100. Rb4 {[%eval 32704,7] [%emt
0:00:00]} Kd5 {[%eval 32742,1] [%emt 0:00:00]} 101. Rh4 {[%eval 32706,5] [%emt
0:00:00]} Ke5 {[%eval 32744,1] [%emt 0:00:00] (Kc5)} 102. Kg8 {[%eval 32706,10]
[%emt 0:00:00]} Ke6 {[%eval 32740,1] [%emt 0:00:00] (Kd5)} 103. Rd4 {[%eval
32720,5] [%emt 0:00:00]} Ke5 {[%eval 32738,1] [%emt 0:00:00] (Ke7)} 104. Rd1 {
[%eval 32724,5] [%emt 0:00:00]} Ke4 {[%eval 32740,1] [%emt 0:00:00] (Kf6)} 105.
Rd2 {[%eval 32720,5] [%emt 0:00:00] (Kf7)} Ke3 {[%eval 32738,1] [%emt 0:00:00]
(Kf5)} 106. Rd5 {[%eval 32716,5] [%emt 0:00:00]} Ke4 {[%eval 32740,1] [%emt 0:
00:00] (Kf3)} 107. Rd6 {[%eval 32716,5] [%emt 0:00:00]} Ke5 {[%eval 32738,1]
[%emt 0:00:00] (Kf3)} 108. Rd2 {[%eval 32720,5] [%emt 0:00:00]} Ke6 {[%eval
32738,1] [%emt 0:00:00] (Kf5)} 109. Rd8 {[%eval 32720,5] [%emt 0:00:00]} Ke7 {
[%eval 32740,1] [%emt 0:00:00]} 110. Rd1 {[%eval 32722,5] [%emt 0:00:00]} Ke6 {
[%eval 32740,1] [%emt 0:00:00] (Kf6)} 111. Rd3 {[%eval 32720,7] [%emt 0:00:00]}
Ke5 {[%eval 32738,1] [%emt 0:00:00] (Ke7)} 112. Rd7 {[%eval 32704,7] [%emt 0:
00:00]} Ke6 {[%eval 32738,1] [%emt 0:00:00]} 113. Rh7 {[%eval 32700,9] [%emt 0:
00:00]} Kd5 {[%eval 32738,1] [%emt 0:00:00] (Ke5)} 114. Rh6 {[%eval 32700,5]
[%emt 0:00:00] (Kf7)} Kd4 {[%eval 32738,1] [%emt 0:00:00] (Kc5)} 115. Rh4+ {
[%eval 32704,5] [%emt 0:00:00]} Ke5 {[%eval 32740,1] [%emt 0:00:00] (Kc5)} 116.
Rh3 {[%eval 32686,10] [%emt 0:00:00]} Ke4 {[%eval 32738,1] [%emt 0:00:00] (Ke6)
} 117. Rc3 {[%eval 32698,10] [%emt 0:00:00]} Kd5 {[%eval 32736,1] [%emt 0:00:
00] (Kd4)} 118. Rf3 {[%eval 32686,7] [%emt 0:00:00]} Ke4 {[%eval 32736,1]
[%emt 0:00:00] (Kd6)} 119. Rh3 {[%eval 32698,6] [%emt 0:00:00]} Kd4 {[%eval
32738,1] [%emt 0:00:00]} 120. Ra3 {[%eval 32700,5] [%emt 0:00:00]} Ke4 {[%eval
32738,1] [%emt 0:00:00] (Kc5)} 121. Ra6 {[%eval 32696,12] [%emt 0:00:00]} Kf5 {
[%eval 32738,1] [%emt 0:00:00] (Kd3)} 122. Ra2 {[%eval 32722,5] [%emt 0:00:00]}
Ke4 {[%eval 32738,1] [%emt 0:00:00] (Ke5)} 123. Rg2 {[%eval 32694,8] [%emt 0:
00:00]} Ke3 {[%eval 32738,1] [%emt 0:00:00] (Kd3)} 124. Rg4 {[%eval 32692,12]
[%emt 0:00:00]} Kf3 {[%eval 32740,1] [%emt 0:00:00] (Ke2)} 125. Rg7 {[%eval
32704,6] [%emt 0:00:00]} Ke4 {[%eval 32740,1] [%emt 0:00:00] (Ke2)} 126. Kf7 {
[%eval 0,100] [%emt 0:00:00]} Kf5 {[%eval 32740,1] [%emt 0:00:00] (Kf3)} 127.
Rg2 {[%eval 0,100] [%emt 0:00:00]} 1/2-1/2