Clean Up Computer

I already have a slow internet connection, but now every time I get on the internet it freezes or says not responding. Then if you press ctrl-alt-delete a blue screen comes up. You press a key it goes back to the screen and is frozen so there's nothing else you can do, but to start your computer all over again. I do it every single time. I asked jeeves what was wrong and it's saying that I need to clean my registry, but I can't find a way to because spyware and virus scans don't help they don't see a problem.