I won't list them all such as root kit, trojan, PUP, and others but suggest you read Grif's note on free tools to scan for other than a virus. The days when you could expect your antivirus to protect your PC are over.
You might ask why and one reason is an Adware company sued over an antivirus company blocking their adware. Sad it came down to that.
OK, read http://forums.cnet.com/7726-6122_102-5509131.html?tag=posts;msg5509131
Bob
For 3 days now every morning as soon as I turn on my computer I get a call from an Indian sound person claiming to be Microsoft or some other entity claiming they are receiving reports that my computer has various issues that they have monitored. They want to fix problem through remote access.
Scam, I know that, but why every morning as soon as I turn on computer?
All antivirus is up to date. Three days in a row doesn't seem to be a coincidence that they call as soon as I turn on computer.
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