No files are write-protected. The user who had this tried the game on another system and the original key worked without any problems on that computer. The main computer the user had didn't for some reason. There's otherwise no directory structure - the key must be in the same directory as the the game itself. It's just two files - the EXE itself and the key file. Other files do spill out as well from use such as game save files (including a single backup file), the error log (of which I used to resolve that user's issue), etc., all in the same directory as the EXE itself. This is the one main thing I don't get at all.