Performed what is called a XP REPAIR INSTALL.
It normally does not wipe out the machine and I don't write the instructions here. Just ask google about XP REPAIR INSTALL.
I did an AVG Rootkit scan which turned up "c:windows/system32/userinit.exe" as a dodgy file.
I removed it and now the machine won't login when I boot the system. With a bit more digging it seems that this file was actually the login information within the registry and as it can't find a valid user/password it just keeps asking me click the user name and login.
When I click it just loops back and throws back up the window, asking me to click the user name again.
I suspect that the AVG Rootkit gave me a "false positive" and this wasn't a rootkit after all.
Is there a simple way I can access the registry and reset the userinit.exe file?
I've tried selecting "last good configuration" which didn't work.
I also tried to download Bart PE on another machine (running Vista) to set up a boot CD, but it wasn't particularly clear how to go about it, so I tried using the XP System Recovery app on the install disks. This got me into a C: prompt, but couldn't figure out how to get regedit going (i was going to simply try reseting the registry value for the login)
Is there a way to open a list of configurations, so I can go to the previous config to that one? For obvious reasons I'd prefer to avoid reinstalling XP and losing all my data.
The crashed PC is in another location, which I won't be visiting for another week or so, so in the meanwhile, any tips would be hugely appreciated! Will post how I fare once I manage to have another go at fixing it.