http://en.wikipedia.org/wiki/Threefold_repetition
"In a game between grandmasters Anatoly Karpov and Anthony Miles, Karpov, with less than five minutes on his clock, claimed a draw by repetition after checking his scoresheet carefully, whereupon Miles gleefully pointed out to the arbiter that in the first occurrence of position, Karpov's king had had the right to castle, whereas in the second and third it had not. Tournament rules stipulated that a player be penalized with three minutes of their time for incorrect claims, which left Karpov's flag on the verge of falling! By now, Miles had had his fun, and took the draw."
In a chessmagazine I read a slightly different story: They played on with Karpov only having only about a minute left, but that Karpov still made the draw. Im not sure which version is correct.
I found a game that may be this one, but here it´s Miles that could have castled in the first position:
Karpov - Miles 1986
1. d4 Nf6
2. c4 c5
3. d5 b5
4. cxb5 a6
5. e3 Bb7
6. Nc3 Qa5
7. Bd2 axb5
8. Bxb5 Qb6
9. Qb3 e6
10. e4 Nxe4
11. Nxe4 Bxd5
12. Qd3 Qb7
13. f3 c4
14. Bxc4 Bxc4
15. Qxc4 d5
16. Qc2 dxe4
17. Qxe4 Qxe4+
18. fxe4 Nd7
19. Ne2 Nc5
20. Nc3 Nd3+
21. Ke2 Nxb2
22. Nb5 Ra4
23. Nc3 Ra8
24. Nb5 Ra4
25. Nc3 Ra8
26. Nb5
View Board
And this should be where Karpov wrongfully claimed a draw, but I´m not sure that this is the correct game. Does anyone know?