Doing the following may crash FoldIt in large puzzles:
First, press Ctrl+Shift+B to enter full atom w/ hydrogen mode.
Set sidechains to "show all."
Load a solution that's not your high score.
Press Ctrl+B to restore best –> foldit crashes.
Note that hiding sidechains prior to the last step would prevent the program from crashing. Does that mean the crash is due to the program trying to refresh too many objects at once? For your information, I'm running Foldit under Win Vista SP2.