I have run every scan available and my computer says everything is fine but my FireFox is running sooo slow it takes up 100% of my CPU usage. But the rest of my computer runs great is it possible that FireFox alone has a virus? Any thoughts?

Have you closed and reopened FF? What extensions are you running? It could be a conflict there. You can also post a HighJack This! log in that section of the site and I will have a look at it for you.

The only extension's I'm running is the weather, if that is what you mean by extention, but i uninstalled it and it still is running slow hijack this shows nothing. it's been like this for a couple of weeks I just havent had the time to run all my virus/spyware programs until now. but like i said nothing is showing up. it takes about 1 minute or so just to open and the pages load extremely slow i thought it was my internet connection. but that doesn't explain why it is taking up so much of my cpu usage.

Try a program called FireTune

http://dl.totalidea.com/files/public/firetune.exe

You can view extensions by going to Tools on the tool bar and looking in Add-Ons. You might try doing an reinstall of Firefox. Files could have become corrupted.

thanks everyone I think that fire tune worked(for now) I need to upgrade my pc it's getting out of date I need more ram i think thats my biggest problem

Because of the way FF caches pages it will use more and more RAM the longer the browser is open. Closing and restarting clears that out and will lower your resource usage dramatically.

"Because of the way FF caches pages it will use more and more RAM the longer the browser is open" I did not know that! I love this site I learn something new everyday. 1 more question? ever since I installed site advisor alot of pages wont display it says server not found. Why? it is the site advisor because these are sites ive gone on before and now I cant my mom, sister & brother are complaining about the same problem ever since I installed it on there cpu's also.

Did you also install a hosts file or maybe IE-Spyads? Can you give a few links? SiteAdvisor doesn't block sites just rates them for safety.