"The broadband link is currently not available"

Hello,

One of computers at work shows "AT&T Gateway Alert Notification. The broadband link is currently not available" message in the internet browser everytime I open Internet Explorer or Firefox. That particular computer connect using wireless card to our wireless router. I checked and the computer is getting ip address. In the lower right corner it is showing that wireless connection is working fine. When I go to command prompt, I can ping my router, I can ping www.google.com also. So I assume that I am connected to internet. I scanned the computer with MalwareBites and Superantispyware (I cannot get newest updates for them- shows error message).
Has anyone any ideas what I am dealing with.

Thanks for your time

Nerita