Registry virus

When I click on Internet explorer my computer freezes up. I can play online but any attempt to use search engine freezes my computer. When I called Dell the advanced tech support guy said it was a virus in my registry . When I try to run virus scan of course it crashes when it get to that point. I can't restore to an earlier point either. I was told I had to reformat or fix registry but don't know how and my comp is over 4 years old and refuse to pay $150 to have someone fix it. Any help would be appreciated. I have a Dell xps 410 and running windows xp