Bad Request (by 2 users)

Hi, I bought a Acer Extensa 5420 computer lab, and for some reason now whenever I go onto certain websites such as hotmail.com it gives me a bad request (invalid verb)... What is that. I can't figure it out. Is it my computer... I had this computer for five months. It started about 3 and half months ago. I can't figure it out. I even bout a Registry Easy program. It's still not helping. I know I don't have a virus because I have Trend Micro Internet Security. Can some one help me out.