Tosh
Not sure might be causing that. It may be an idea to check the following:
Other internet services are working normally
Port 80 is being forwarded from your router's firewall
Try rebooting the router (ensure that you either know your router settings or
have them backed up before attempting this)
If all else fails, try reinstalling IE from
here.
But there is a better way - development of IE for Mac stopped years ago and support has recently been discontinued. Even Microsoft themselves are recommending that Mac users move to a 'more modern browser'.
I use
Safari myself, plus I also keep a copy of
Firefox handy for the few (usually M$-centric) sites Safari has a problem with. IE was fine in its day (three years ago), but these newer browsers are far faster, more stable and render pages much better than IE ever did. Go on, treat yourself - try the latest stuff and see what you've been missing!