Quote (Pick @ 24 May 2011 20:57)
i tried reinstalling firefox(what i normally use) and it didn't work, so i tried internet explorer 7, and that didnt work
why ie 7 ? use 8 on xp 9 on vista, try clearing your passwords as well as everything else, if you use autocomplete clear that as well
sorry don't know what else to try, apart from a friends pc if you can get access to one
absolute last resort, restore your pc to before you started getting this problem, if you can see if that helps

seriously doubt avast is your problem, i've been using it' for a couple of years and never caused me anything like this.
have you tried a spyware sweep ?