Perhaps you, like me saw a rash of sites giving the error "Internet explorer cannot open the Internet Site" yesterday. At first I thought one of my machines was messed up. Then I saw it on another machine. This one running XP. A virus perhaps? I can't recall doing the same thing on both machines. How would I get a virus on both? A worm maybe? Updated the antivirus just in case. This morning the errors seemed to be gone but still the mystery. What caused it?
It appears that a tool called SiteMeter was causing the problem. Mystery solved. More detailed information here.