Tip from an old IT hand (been doin' this stuff since the 70's):
Anti-Virus software doesn't always catch everything on a computer. Go to
Free software downloads and software reviews - CNET Download.com (Very safe site)!
1. Download, install & update the following software:
Malwarebytes Anti-Malware 1.46
Ad-Aware Free Internet Security 8.3.3
Run Full Scans with BOTH programs and remove anything they find.
2. The best 'free' AV program you can find, IMHO is AVG Anti-Virus Free Edition 2011 10.0.1136 (available from the same site).
3. Don't use IE (Internet Explorer). Download and use Mozilla Firefox as your browser (
Mozilla | Firefox web browser & Thunderbird email client). I would then install the 'extensions' AdBlock Plus and No-Script for added safety.
4. Finally, install SpywareBlaster 4.4 (again, found at
Free software downloads and software reviews - CNET Download.com), use with Manual update, and mark your calendar to update the program definitions and 'enable all protection' once a month.
This will help keeping your computer as clean as it can possibly be; but unfortunately, will not help with keeping the 'vendors' computers clean (unless they read this post ;-)