Unable to start Windows XP

[FearTheAtlas]

Ok, this has happened before, and for some reason it fixed itself. I was playing Mafia, when all of a sudden my computer froze up, then restarted with no warning at all. Now when I try to start it, it does the beginning scans, fan speed all that jaz but before the windows loading screen comes up it says something like this:

We are sorry for the inconvience, but Windows could not start properly. This could be do to new software or hardware change.

then it goes on to say if such and such has happend choose start windows normally, or if such and such has happend choose use last good known configuration. I'm very concerned about this and I have no idea what to do, if anyone can help or has an idea, please post it. Thanks.