What steps will reproduce the problem?
1. The Computer Mated me;  
2. I try to undo
3.

What is the expected output? What do you see instead?
Expected: ability to undo; Seen: DialogBox Title:Wait your turn; Caption:
You can take back your last move when it is your turn

What version of the product are you using? On what operating system?
Latest download (June 5th 2009); XP (not really OS specific I assume though)

Please provide any additional information below.