Serious Malware Problem - no safemode, user password reshuffling, no desktop

Hello MajorGeeks support folks -

After leaving my XP Home desktop PC to the care of others for some time, I have recently found it to be thoroughly infected by some seemingly deep malware. A HijackThis report is, unfortunately, impossible to run at this point.

First, the machine will automatically initiate a 60second shutdown upon reaching the user login screen, and I have not yet gotten to a point where I can disable it through a command prompt.

On the rare occasion that this countdown is not initiated, I found that the password of the two users registered on the machine had been automatically reset (and later found it is continually reset).
After using a password recovery boot CD to at least try to log on with recovered passwords *I noticed the Administrator account was not passworded.*

After logging on one of the users with a correct password all that is displayed is "WINDOWS WARNING MESSAGE!" "Warning! Spyware detected on your computer!" "Adware.Virtumonde" "PrivacyRemover.M64" with a solid pale blue background. Interestingly *I was able to do a Ctrl+Alt+Del to get to the task manager, which opens up the ability to potentially run the cmd prompt.*

Additionally, logging into any safe mode is impossible and simply crashes the system.


I've already downloaded a series of programs to tackle this issue, including AVZ, UBCD, etc. but am still not quite sure which path to take at this point. Any help... suggestions, links, whatever, would be truly appreciated. I don't have a recovery disk and so my only option is to dig in and root this thing out.


Thanks again for reading this and if there is any more information I should be able to provide even with the access restrictions I'll do my best to get them.