Your backups may also be corrupted ( or at least a field's index may be corrupted ). Problems like this can "lurk" for a while before you trip a big enough response to crash the filemaker on the database.
Try rebuilding the indexes of the fields referenced in the script. (Turn indexing off in storage options, Click OK to leave the dialogs and return to the database layout. Then reopen the field definitions and turn indexing back on.)
You can also rebuild all a file's indexes by importing all the records into a clone of the file.
If all else fails, you can do a recover on the file, check for any indications that a problem was found and fixed and also test the recovered file to see if it works correctly (even if no problems are reported ). If recovery fixes the problem, best practice is to replace your file with an older copy that doesn't show this problem if this is possible.
Alright, we'll try that out. Thanks for the quick reply.