No solutions yet, just an update. My partner's son ran chkdsk on his laptop and we now have *4* computers in the house with the identical "bitmap volume errors" messages (except for the one I fixed with a reinstall and adding Diskeeper Pro). They all upgraded to SP2 via "Automatic Updates". Since one is a Dell, I've been talking to them. They suspect a boot sector virus and I sent a copy of boot.dat to Symantec Labs for testing (NAV says *no* boot sector virus but I'll wait until I hear back from Symantec Labs). On the Dell they want me to run a debugging utility (only available to people with Dells). That will remove all partitions and kill whatever is in the boot sector. Then I have to run FDISK on it. Then they want me to reinstall XP Pro. I finally heard back from Microsoft escalated support. He has no solutions, but is insisting that Diskeeper Pro is the root of all my problems. Even though I had the same problems with just SP2 and no other apps on my reinstalled hard drive. And the only thing that saved it was installing Diskeeper Pro. Whatever, he is mailing me a new XP Pro cd with SP2 already "enmeshed" on it. Okay, I'll try anything. It may be that since SP2 is such a big upgrade, that it runs better from a CD with it already part of the install program. IOW, installing it over XP with SP1 might be leaving some strangeness on your hard drive to cause boot sector problems. Just a theory, anyway.