Windows file protection errors

I'v never had this problem before, but i have to keep an xp cd in the cd-drive, or windows give me file protection errors that important files are being replaced, why is this now all of a sudden,
went here http://www.microsoft.com/whdc/winlogo/drvsign/wfp.mspx#XSLTsection130121120120
also been having problems getting windows to boot up, before reaches windowsXP logo screen, just freezes as black screeen, does nothing after that have to reinstall windows constantly..........

 

Is this a legal copy of windows?

Have you formatted and installed and having the same thing occur?