IE9 - Unable to include port numbers in URL

I'm running IE9 on Windows 7.  I have a server with separate http services running on ports 80 and 8080.  If I type 192.168.1.250 IE opens the page (at the service on port 80).  However if I type 192.168.1.250:80 or 192.168.1.250:8080 I get redirected to search.imesh.com with a search for 192 168 1, which I assume means the page cannot be found.

Chrome works as expected (ie opens all the pages), so I feel it must be something peculiar to IE.

Can anyone explain what the problem is and how to fix it?

Many thanks.