HDMI Output on a laptop

My mothers laptop (pretty basic, with 880M or 8800M nvidia fiik which, 3gb of RAM, Win7 Pro) Has HDMI out, but wont push video through, tried 2 HDMI cables. Both known working and tested with other equipment to verify. Both nvidia control panel and the integrated windows screen resolution show the TV as being connected, and lets me select resolution, location as well as mirrored, extended and show only on desktop 1/2. Nothing will actually output video to the TV though. Help?

updated drivers?

Tried installing the newest gforce drivers Janus, but it just made the screen go perma black. Had to do a restore in safe mode to get that sorted out. I cant remember which drivers it is running atm, but they arent that old (2-3 releases old I think) Havent had a chance to test, but I may have to do the whole "Connect to a projector" bit if all else fails.

This is going to sound crazy, but are you sure you aren't using the TV as extended desktop? Try moving the mouse pointer over to the TV.

(This is coming from my neanderthal brain but I might be right)