Please help with virus / antivirus software issue?

I have a HP Pavilion running Windows 7 OS. I am pretty sure I have a virus probably a root kit. I was using AVG Free 2011 backed by Malwarebytes and Ad-Aware. None of these picked up anything. I uninstalled AVG to try Avast Free Edition and it found nothing either. However, I cannot get AVG to completely uninstall. I had to do it three times just to get rid of the primary file and icon but I am still getting requests to run an "initial scan". It is also still listed in my programs list but I can no longer click on it as is says it is uninstalled. A search of the entire hard drive for "AVG" turned up nothing but it is still asking for an "initial scan" to be run. I am willing to chalk this up to user error but I wouldn't know what I am doing wrong. Could this file be where my virus is hiding ? Thanks in advance for your help and suggestions.