My computer logs me out of the net and will not download antivirus.

I had someone try to install some AVG antiviris and my computer wont download it, it wont download computer cleaner and it wont install upgrades with the little yellow shield in my lower righthand corner. What do I do?

Hello.

Please visit this webpage for instructions for downloading and running ComboFix:

http://www.bleepingcomputer.com/combofix/how-to-use-combofix

Post the log from ComboFix when you've accomplished that.