That was probably me
You can use this free scanner/cleaner to get a second opinion about your computer's current status. The free one isn't real time protection(resident), however. It doesnt stop or block problems from getting in, but cleans up after the fact.
www.malwarebytes.org
There are some free versions out there, but they are for residential use only. I'm not aware of any free for use in a business environment. Like anything else, you get what you pay for. The free ones or the free versions of pay products are usually very limited in what they can do, and will often only get about half of the bugs. Many of the free ones will only do viri, but not adware / spyware / scumware / malware / phishing, etc. Some wont do IM or EMAIL scanning. Most will give daily pop up ads, encouraging you to buy the fully functioning (pay) version.
For residential use: AVAST, AVG, AVIRA, COMODO, PCTOOLS, etc
Here's a very recent article that compares six free residential programs:
Can You Trust Free Antivirus Software http://www.pcworld.com/article/170587-2/can_you_trust_free_antivirus_software.html
It rates Avira as the best of the freebies, but doesnt like the daily pop up ads.
Comparison reviews:
http://www.pcworld.com/article/170674/free_antivirus_software.html
My current favorite is Kaspersky AntiVirus. This is a pay program, suitable for home use or business use, and is quite reasonably priced for multiple computers. They offer a free 30 day demo version.
Demo Link The new Kaspersky 2010 just came out, which I haven't tried yet. I'm still using the 2009 product for 16 computers in our home and plaza.
NOD32 is another good one worth mentioning.
If your pc is old or has less than 1gb RAM, I strongly advise against any Norton or Mcafee products. These products are popular, but have an unusually high demand that slows most pc's down.
In my opinion, this is an important issue for any business. It's well worth the investment and peace of mind to use a pay product. Downtime and file loss are costly, and a/v programs are cheap. (about $15-$20/yr when youre doing multiple machines or multiple years)
Most offer a free 30 day demo version, through their websites.
Before installing ANY product, be sure to fully remove the old one and REBOOT first. Some programs will become corrupted if this isn't done first.
Best regards and happy hunting for the right one
Mike