Do you have another computer with Windows XP on it at your house? If you do, what I want you to do is take the hard drive out of your computer and hook it up on the other computer. The easiest way to do this is to remove the IDE ribbon cable from the CD-ROM (or CD-ROM's if you have two of them connected to the ribbon) and connect it to the hard drive from the problem computer, remember to connect a power cable to it as well. Then boot up the computer. During boot up, a window should pop up saying that the drive needs to be checked for consistency and it will run a scan of it. Hopefully it will do this and fix any errors it finds. Once it's done with the scan and you are at the desktop, I want you to backup any important files that you would like to keep. MP3's, pictures, documents, etc.... Once you are done backing things up, shut down the computer, remove the hard drive and put it back into it's original computer. Boot up the computer and see if the same error bubble continues to appear. If it does, then try to do a repair installation again.