I manage to crash GE somewhat regularly, but I can't always remember what I did to get the program to break.
This user input though, consistently breaks the program. I use a Tablet PC that runs Windows XP Pro --Tablet Version.
You probably already know about this situation but on the outside chance that you don't:
Create 2 actors:A1, A2
A2-->On keydown Event (Return)
create actor A1 (do some action )
Now, remove Actor A1.
Go to A2 and try to edit the Event that you created. Boom! GE blows up.