Here is how you should proceed,

1. Clean up your hard disk with Windows Disk Cleanup utilty


2. If you got excessive pop-ups and/or you are not able to gain
control over your pc, restart computer into safe mode (ie, by tabbing
F8 at restart, and choose Safe Mode/Safe Mode with networking).


3. Disabled suspecious Startup Items with System Configuration
Utility
(start->run---(msconfig))


4. Turnoff System Restore (start->run (rstrui.exe))


5. Run a full system scan with your antispyware program or do a
manual
spyware removal


For more instructions and tips, check http://xantivirus.blogspot.com


Enjoy!