I have just spent a day trying to recover from a similar attack to the one mentioned above. Tried 4 different anti spyware applications but the problem remained. In desperation I rang a friend in the computer business to see if he had any ideas how to proceed and he emailed me a small application called combofix. Unzipped it to the desktop, ran it and 20 minutes later my machine is back to normal. Cracking little program. It might just solve your problem. Its freeware and readily available on the net.
Good luck
Raven