I had one machine that was completely unresponsive, but I could get Task Manager up, so I put in my USB key full of spyware and virus fixes and other utilities to try and fix it. I got nowhere;
I have since put the USB key into three other machines, and after the 2nd of those, I realised that the first machine had infected the key, and now the key was infected these machines.
Errors I have seen so far include;
WINLOGON.EXE error on startup.
Machine spontaneously reboots
Machine logs in but no explorer.exe hence no desktop icons or task bar.
On the first machine I have;
Scanned the hard drive out of the machine with NOD32; It found a range of files it thought were bad but did not specifically know what they were infected with, and some of those were windows system files (and some looked like they were, but I did not find comparable files on a clean windows machine).
I had NOD32 delete all the infected files, and I copied over good copies of the true windows files from another machine. After that, the computer still booted and logged in but still did not have icons or the start menu / task bar.
A repair install on that machine got it working, but I cannot run programs; Clicking IE, for example, does nothing, it just doesn't start up. I tried to uninstall the AV software (Norman) but that gives an error. (I wanted to reinstall it as one of the infected files was from it too).
At least one of these machines I am desperate not to reformat, so any advice on where to look or what to try would be gratefully recieved.