Last night after my McAfee anti-virus downloaded some updates, I got a message saying my XP machine was going to reboot in 60 seconds. Being annoyed by this (as I was doing stuff) I didn't really read it and just cursed McAfee for forcing a reboot on me so issued the "shutdown /a" command (to abort the shutdown) then a minute later it happened again and all my desktop theme disappeared (start bar went grey).
(If you are looking for a solution please go the end of my ramblings.)
I thought I'd better let it reboot if it wanted to so I closed what I could.
When it rebooted there wasn't even a taskbar and not much worked (including the internet). PANIC!!
After a lot of fruitless tinkering I decided to go to bed.
This morning, with a clear head, I worked out that the system file svchost.exe was missing (this is needed for a lot of system services to run including the one that provides the pretty themes). Luckily I had another computer of the same XP version around so I took the file from there and transferred it. Success, after a reboot if all seemed to be working but then I get the reboot message again. This time I read it and it said the RPC service had stopped working so the machine was rebooting.
Much googling on the other machine let me to believe it could be a virus (but the ones referenced were "fixed" in 2003).
Much disk checking and "virus fixing" ensued.
However, I eventually found that McAfee itself was the problem.
There had released a new virus definition file which was erroneous marking the vital svchost.exe as a virus and quarantining it!
I downloaded the "SuperDAT Remediation Tool" (from the link above) and ran it in safe mode (press F8 before Windows startup) and it fixed the problem. (Then I updated McAfee) Phew! I only installed McAfee after coming to the end of my tether with Norton, I guess now I should try the free AVG which has had rave reviews (even from my Dad after being recommended to him by Sony for his new laptop) and isn't a system hog.
Just thought I'd put this up there so people might find it if their computers have stopped working (assuming they can get to the internet, not sure what I would have done had I not had a second computer handy!)
UPDATE: Arrghh! It's happening again svchost has gone! This is not over! (Clearly their "fix" doesn't work)
UPDATE": When I tried to run their standalone dfinition update in safe mode it said "Error: No qualifiying McAfee products found". I have now uninstalled McAfee and installed AVG. The world is a better place...