You may have noticed adobe flash popping up on your screen asking to run an update. You may have clicked cancel annoyed at this interruption. I strongly recommend you ensure keeping adobe flash up to date, due to the fact you can get a virus simply by viewing a webpage with an infected flash script running.
If you own a mac beware of a program reportedly posing as security software called "MACDefender". This software is itself a virus, and will cause problems.
Are you using AVG free? has it been good protection so far? I am currently no longer installing AVG free on user's computers who do not have paid antivirus protection. I am now installing Microsoft's own antivirus protection called "Security Essentials".
If you have recently come accross a program called "Security Tool" that is running on your computer, and claims to have found viruses, unfortunately you do have viruses - and "security tool" is the culprit.
Virus Protect Pro - Warning - Do not install this "virus checker" under any circumstances, it is infact a virus pretending to be a virus checker.