OK, remember I built this computer. You can discount a lot of elementary problems that might be encountered by others. Windows XP is only a few months old. Less than a year. I tried a System Restore to Dec 26, just because it seemed like a good time. Windows XP appeared to be doing the job, then rebooted only to tell me the System Restore wouldn't work. I ran Disk Doctor again, and it complained that it didn't recognize some partitions on the D drive (data). It offered to scan the drive and fix the partition tables. It is still scanning, looking for DOS partitions. If you have a computer with a C drive, that usually has the operating system. It is the first hard drive on the computer. In my case, the C drive has the operating system and programs. The D drive is a data drive. Mostly Poser Stuff. There is some stuff I had downloaded. Also I was redoing some CD's to better organize. Of course it is sometimes hard to say which is which.