You got the dreaded Zlob trojan (well that trojan is old and there's a bigger badder one in place now).
1. Go to Link
MUST BE THIS SITE AND NOT ANOTHER.
2. Download Spyware Doctor from that site and install it (if you must use a different computer and a USB key or install this to the USB key, do it).
3. Once Spware Doctor is installed, run Smart Update.
4. Restart computer in Safe Mode.
5. Run full system scan and deleting all infections. Repeat until a full scan comes up clean.
6. Restart in normal mode. Run a full scan. If it returns infections, clear them and go back to step 4. If it is clear, you have removed the malware successfully.