Here's a list of things you can use to protect (and hopefully fix) your wayward PC. The best part is it's all FREE (or in some cases, a free trial)! I have them listed in the order the steps should be performed.

1. Disk Cleanup. This is part of Windows (Start, Programs, Accessories, System Tools). This will clean up items in the recycle bin and in various temporary folders. Do this before any scanning so you don't have to bother checking temporary files.
2. Anti-spyware scan. You need to download, install, update and run at least one of the following:
   • Ad-Aware Personal from LavaSoftUSA (link)
   • Spybot Search & Destroy from Safer-Networking (link)
   • X-Cleaner Free from XBlock (link)
   • X-Cleaner Micro Edition from XBlock (link) - this one is an online scan and uses ActiveX
   • Microsoft's Windows Defender beta (link)
   • ewido network's online scan (link) - this also uses ActiveX
   • ewido network's ewido anti-spyware (link)
3. Anti-virus scan. Unlike the anti-spyware, you should only have ONE anti-virus program installed. Download, install and update one of the following programs. You may want to run one of the listed online scans first, since some viruses will disable installed anti-virus programs to avoid detection.
   • AVG Free Edition from Grisoft (link)
   • HouseCall from Trend Micro (link) - this is an online scan that will use either ActiveX or Java, so you can use it with FireFox is that's your preferred browser.
   • Symantec Security Check from Symantec (link) - this is also an online scan that uses ActiveX.
4. Windows Update. This should be in your Start menu. If it is not, you can go to windowsupdate.microsoft.com. Make sure that you at LEAST have all of the critical updates installed. Once you install and reboot, go back to make sure there are no additional updates triggered by the ones you just did - IE is particularly notorious for having further updates once you install a new version, for example.