The most important thing you can do for your computer to protect it is simply keep it up-to-date. If you're not installing Windows Updates, you're missing a good many security patches that block viruses on their own, without an anti-virus software.
I work as a computer tech and we deal with these issues on a daily basis. Our standard procedure goes like this:
- run a scan using Webroot Spysweeper in Safe Mode
- restart the computer
- run the Spysweeper scan again in Safe Mode.....restart and continue scanning until a scan does not find any more instances of spyware
- sometimes I will also install and run and Adaware scan just to be safe
- restart and boot Windows normally
- check the Add/Remove programs list and make sure all the spyware programs are gone
- check the Program Files and delete and leftover folders associated with spyware
- clear the history, cookies, cache, etc files for all of the internet browsers on the computer
- run Windows Updates and install all of the critical updates
- run ONE MORE spysweeper or adaware scan for good measure
- of none of this helps, we get into registry edits or just reformat the machine
Reinstalling the OS on the hard drive is a good idea if you can, BUT remember if you don't run Windows Updates, all of the same viruses and spyware will come right back on the machine b/c even though you're starting over, your making the machine in a sense older and more vulnerable.