Rename ComboFix.exe to commy.exe before you save it to your Desktop
Disable your AntiVirus and AntiSpyware applications, usually via a right click on the System Tray icon. They may otherwise interfere with our tools A guide to do this can be found here
Click Start then copy paste the following command into the search box & hit enter: "%userprofile%\desktop\commy.exe" /stepdel
As part of it's process, ComboFix will check to see if the Microsoft Windows Recovery Console is installed. This will not install in Vista. Just continue scanning, and skip the console install.
When finished, it shall produce a log for you. Please include the contents of C:\ComboFix.txt in your next reply.