im just saying from exprrience. but i had that problem- what i did was i downloaded mozilla firefox from
http://www.mozilla.org/products/firefox/
i was told from one of my friends (who is a like computer geek) that internet explorer is like asking for problems for your system, but mozilla firefox can help with that problem i hope this helps. if u get the chance go and delete ALL cookies. some problems are caused by those things.
one more thing most of those "anti virus" programs dont do anything. something that im sure that works is AVG anti virus. i dont know if they charge for there program, but it is good. if so then if u go to windows.com there is a program called 'beta' that i have that has saved my computer from a system meltdown. If u have a service SBC they offer their antivirus program that can show u more than any other anti virus thing. but dont delete anything unless u know what your doing.