How come IE8 does not allow a port number at the end of a URL?

Typing "www.example.com" works fine in IE8, but when I enter "www.example.com:8000" it doesn't work (I know it works for some people).

Port 8000 is necessary because I do a lot of web development testing and I run web servers on that port.

The error I get reads:

The webpage cannot be displayed.
Most likely cause: Some content or files on this web page require a program that you don't have installed.

Of course, on the same Windows machine Chrome and Firefox both work perfectly fine.

IE is finicky when it comes to adding port numbers - if you want to use them, you MUST add http:// at the front, so try http://www.example.com:port