It appears (subjectively) that Foldit is more stable when the Undo Graph Length is set to less than 100. Is it possible that Undo has an overflow problem?? I run with Graph Length 97 and seem to experience fewer crashes than others. Worth checking out?? VTX.
It's quite possible this memory usage has some effect. But some people reported problems even after resetting their options, which should return the maximum length to 25. You can adjust the Memory Usage in the Graph Properties menu to store some undo information on the disk.
How about setting this value not in runtime?
I can imagine, that a change of the undo length can cause an error, while fold.it is running, but not, if it is changed before the game is intialized.
Changing buffer length can also cause instability in other applications.
So, I would recommend, if the value is changed, that you give a message "restart game to accept changes" and change the starting information.