OK, it's a rootkit or similarly obnoxious and persistent infection.
Go download unhackme at
http://www.greatis.com/unhackme/disable system restore, (right click "my computer", go to "properties", go to "system restore", check "turn off system restore", click apply, wait til it's done, then click 'ok')
install unhackme, run "check me now", then if that says "congratulations, no rootkit found", click "check startup processes" or whatever, let it reboot.
Remove anything that doesn't have "svchost" in it, and don't let it remove "catchme" if it shows up.
It will reboot again, if it got what you told it to out, it will check, then boot up to your desktop. If this happens, then run combofix again.
If unhack me keeps finding #$%* on every boot up that it couldn't remove, let me know what it is. We'll go from there.