Originally Posted by delphidb96
I don't know what the extension is, but under WinXP's Explorer it shows up as a PARAM file and it's name is mobipocket.
The filename is mobipocket.param and you are right that for example the font used is stored there. But you are wrong in your conclusion that it is a problem removing. I just tested to rename it and it was properly recreated and new settings was stored in the new file and everything worked perfectly.
So your problem is something else and as I have said it is probably a corrupt file system so why do you not check this? People have posted how to check it in Windows here and it should be easy to google.