I have a relatively new Powerspec computer (i5 quad core processor, about a year or two old) and just grabbed a new relatively inexpensive ($40?) graphics card. It has 1 DVI, one VGA, and one HDMI output.

I have two (different type) monitors plugged into the DVI and VGA slots, and they work great. However, I cannot seem to be able to get a third monitor in the HDMI slot to work. I can see the monitor (and monitor info) show up in display settings. However, if I try to switch the monitor to 'on' and click apply, nothing happens.

Anyone have the slightest idea what the problem might be? (It's a Radeon graphics card FYI; if I remember right I think it was the Radeon 4200?)