os is invalid on booting up mpc 4000

I've been having this problem for about a week or so, when i turn my 4000 on sometimes it gives me an error message that says my os is invalid, if i turn the 4000 off and turn it back on again it just boots up properly but sometimes it takes a few times for it to get correct, i just want to know if any else has had this problem and how they fixed it! any help is really appreciated!!!!!

did you try to reinstall it??

nah, haven't tried that yet, actually been away from my 4 since i posted this, I'm gonna give this a shot later on 2nite, thanks for the help!!