I played against the AI, and after 10 or so moves, after I leave the calculator for about 2 minutes without pushing a button, I try moving the cursor, but the arrow keys stop working (the cursor stops flashing also). I know the program didn't freeze, since the grayscale was still working (not black and white lines). I was forced to pull a battery. I have OS 2.43, but I don't know why this occurs.

Arrrrg. (Pirate) It got stuck in some endless loop inside the AI. That should not be easy to find so it might be a while before I fix it.
Edit:
I should make a button to abort the AI.