Forget about the error message and what it means technically.
If you get these kind of errors dont go doing drastic stuff until you look for the easy solution.
If when level building FPSC returns runtime error messages of the kind you mention in this instance. i.e. it cant find an image.
Then when such errors occur stop what you are doing immediately and think logically what were the last things you did and undo them. If it worked previously then it should after undoing your last moves.
In the case of a missing image FPSC cant find it either due to an incorrect reference, location or spelling error in file name or script references. Correct the error and the message will go away.
The morale of the story is - develop carefully, test often - very often and always try to get around as much or all of your level at every test run to make sure all is in order - that way you can discover quickly when something has gone wrong and stand a better chance of isolating an error quickly.
Dont forget to make backups and copies of your level work - make sense?
You wont get much of a result with FPSC unless you follow tight guidlines when developing and think with a cool head and think logically when things go wrong.
Panicking is the last resort - if you must panic.
