Note that you should have uninstalled the original antivirus before installing AVG and if you are trying Avast you should uninstall AVG first. It's never a good idea to have 2 antivirus programs on the same PC.
Also try MalwareBytes. MalwareBytes is unlikely to conflict with your antivirus.
Can anyone help me? We bought a VAIO computer a few months ago with Windows on it. The virus protection ran out on it a few weeks ago and stupidly did not add anything. The last few days I have been getting very annoying pop ups and it running slowly. I went onto Mumsnet yesterday to look at what other Mum's recommend for protection a lot of you recommended the free AVG. It is still running slowly and still pop ups. When I run it again it says there are viruses to clean up and that I should buy the AVG advanced. I'm not great with PC's (as you can probably tell). Is there something I can get to clean it up.