Is there any chance you could drop by the winmxworld help chatroom? There's a few things it's possible to check, under certain conditions for instance MSN's auto repair has been known to damage the registry key which windows uses to determine where the hosts file is.. something along those lines may have happened, particularly if you see a file called HOSTS.msn in the same folder.
To get to the chatroom enter this in the space next to the filter button on the chat screen
WinMxWorld.com Help_E3D7EFD50D3D
Then hit the Join button
I could post things to look at here, but as you say you're unsure of yourself you may feel more comfy with someone "looking over your shoulder" as it were.