|Try clearing your temp internet files|
IE7: Tools, delete browsing history
IE6 and below: Go to tools, Internet options, Delete Cookes, History and offline files
It might also be a good idea to disable any toolbars installed (such as mywebsearch).
Finally, check your PC for viruses/spyware. I would reccomend Avast/Spybot S&D. Both are compatible with most versions of windows (well 95+) which should remove any "Crap" installed.