i think that u have highjak browser that does not search some sites and wont delete history......i had that before make sure that u are updating ur windows weekly but if u are not u should start doing it and there will be some files that are recommended for ur box and u should download them....... here is this link that skans ur computer and it will say what u need.....and keep windows updates updated to latest time...aight...........

http://v4.windowsupdate.microsoft.com/en/default.asp

have fun

peace