Something additional to check for, on top of what Fax and George have instructed you to do.

Security apps don't always fully remove themselves when uninstalled.
Here are removal apps for Avast and AVG.

Follow the directions at each links. Its not a simple as just running the tool. Avast requires to you boot to safe mode, AVG you must know the exact version of there software to download the right removal tool.

Avast
http://www.avast.com/uninstall-utility

AVG
http://www.avg.com/us-en/utilities