This an nvidia card. You may have to install the nvidia restricted
driver. Go to system/administration/hardware drivers. If it does not
say nvidia accelerated graphics driver in use, then you have to install
it. There should be a way to install it from within that window. I
cannot remember exactly what it was, but when I first installed hardy,
there was a message on the top taskbar that told me to do this so I
clicked on that message and it took me to this window. Sorry I cannot
be of much more help, but I think the restricted driver will help you.