Can't do static IP

Working on a customer's system and am trying to enter a static ip in the tcp/ip configurations. Have done this a hundred times, however have never seen this.
When I select "Specify IP address" in the tcp/ip settings, the entry boxes light up so that an address can be entered, however, the cursor will NOT go in the box. System will not let me enter anything in there.
Have checked for virus and reinstalled network components. It's not the nic, have tried different components. Dell's no help, they just don't comprehend the problem. Can't say I blame them, if someone told me this, I wouldn't believe it either.
Anyone have a similar experience.

Try not using the mouse....use the {TAB} key to switch focus on different parts of the window. If you can't edit it the tab will skip right over the box.