I had this problem before.
Answer to fix this problem: Click start, click run and type c:/, in Vista, when you click start you should see a thing that you can type in it and type c:/, click program files, find the folder called "The Game Creators", click fps creator, userdetails (NOT A FOLDER!), and it should look like this:
[PERSONAL DATA]
YourName=Enter your name here!
YourSerialCode=Enter your serial code here!
YourFullPath=C:\Program Files\The Game Creators\FPS Creator
[LOCALIZATION]
language=english
I can't texture. I'm not an artist.