Comp acting funky (internet specifically)

Every now and then I'll try to go on the web, and when after I open my browser and select a website it never loads and eventually freezes, and I get the 'the program is unresponsive' thing.
When this is going on, I also can't connect to the internet with any of my online games.
But, my connection is fine, because my sister is using it on her computer in the same room.
I think it has something to do with my avast anti-virus, because I got rid of something it had going and suddenly everything worked fine.
Not fixed though, because it always comes back and now I can't get rid of it without disabling the entire anti-virus.
But, it's the only anti-virus I can use right now besides Norton, which I hear and believe sucks.

get rid of two those anti viruses (for the moment) and scan with another av (or online scanner)