One sure way to get rid of the problem is:
1. Remove the drive from the machine.
2. Connect it as a slave to another well protected and backed up machine.
3. Copy all critical files to a folder on the second machine, and scan them.
4. Wipe the original drive, and re-install Windows and all software from the ground up.
I know it sounds tedious, and it is, but it could take less time than trying to remove some of the more tenacious fake AV infections, and it's absolutely more certain to remove all of the infection. It's far better than working for hours to remove the infection and thinking you were rid of it, only to find that it comes back later from some hidden file that wasn't removed in the first sweep.
Infections like this are the reason I preach the value of cloning your hard drive immediately after sweeping it for malware. A "cloned" drive is more than a back up for your data. If your main hard drive becomes infected, do your best to save any files since the last backup, wipe it and clone the backup drive back to the main drive. If your main hard drive fails, the cloned drive is fully bootable and operational, and all you'll lose is any unrecoverable files since your last backup.
For Win XP, older versions of Norton Ghost that boot to DOS work very well. For Win 7 and (ugh!) Vista, Acronis True Image works very well between matched drives.
I mount my backup drive in a mobile rack like this one:
When it's not in use, I keep it unplugged from the system because no virus can jump the air gap to an unpowered drive. When it's time to clone the drive, I power down, plug in the drive and clone to it. When it's done, I power down and unplug it.
As long as you're sure your backup is not infected, no virus can take your last good backup point away from you. Worst case, if your motherboard fails, and you can't replace it with the same model, you'll probably have to re-install Windows, in which case, your cloned drive is still as good as any other data backup system.
Good luck.