ref build: 2012-12-18-52736-win-x86
using W7-64bit
may be duplicate or related to case 845829-993917
... but repeatable errors are more useful, so sequence is:

Opened "Beginner rebuild SCRIPT 1.00" (very basic stuff; from internet)
Made an edit - Commented out a few lines
Ran the script - it worked fine - then goes back to edit screen
Closed the editor - red x button
Clicked on "Example 3 Compress" to open it
Warning: changes would be lost (presume to first edit)
Clicked "yes" (Ok to discard changes)
Windows message: Foldit.exe has stopped working