I have a particularly stubborn subject at work just now that I'm hoping for some input on. It's a Win2k Pro Desktop, about 3 years old. Upon startup, I receive messages that some system files are corrupted and need to be be replaced, and I need to insert the Win2k CD to replace the files. Inserting the CD gets you past the notices with a minimum of fuss, but the problem reappears upon restart. Adding to the fun was Symantec AV's refusal to un/re-install. We have an automated installer for the most recent version that should remove whatever version is currently installed, and it seemed to get most of the original install, but the new version was nowhere to be found. Retries garnered you errors, but nothing useful. Finally had to perform a manual removal of all previous installs, and fell back to the second most recent version, which installed, but would not update. Manually downloading the updates seemed to work fine. At first I thought the installer service was hosed, but obviously, I was able to install progs. Oh, also, the event log was corrupt. I've run chkdsk, but to no good. Nothing seems to faze this thing.
I'm also blocked from getting Windows Updates. I give you the error, but I dozed off writing this twice already; I just can't remember.