RUN YOUR UPDATES!

AVG updates automatically - I have version 8.0 and I set it to scan weekly.

If you install it normally, it will run a scan every day.

Here's Malwarebytes:

http://www.malwarebytes.org/

Go to the green Download button on the left. Run a scan with it daily. It does not replace a regular antivirus update/scan, but can nail bad ones quickly.

Use this before you send your computer to the shop next time.