Why isn't Javascript working on my pc?

I bought this Dell computer about 3 weeks ago. The only major change that has been made to it was that McAfee was uninstalled (had few days left to expire). Now the javascript doesn't work on my IE. I have Windows 7. I try to login to websites and the Login buttons when clicked, do nothing. I get a message saying I don't have Javascript enabled/installed. I've tried accessing different pages but it happens on a lot of pages, some pages don't even display the content, like Hotmail or Facebook, etc. I went to Internet Options but scripting is already enabled. I went to manage add-ons to see if something was blocking it, but there was nothing out of the ordinary there. I even disabled my firewall but nothing has changed. I scanned my computer for spyware but it picked up nothing at all. I don't know what else to do. Any help is greatly appreciated.