The driver depends on the particular hardware, and can usually be found on your manufacturer's site if you search under Support for your model. Go here: http://www.csd.toshiba.com/cgi-bin/tais/support/jsp/home.jsp
, and click on Download.
Alternatively, a very clever member here posted directions on how to identify any hardware that needs a driver. See the second post here: http://www.tomshardware.com/forum/274306-45-video-controller-compatible-driver-windows-free-download
, from Saga Lout.
Please satisfy my curiosity: how do you know that this is a driver issue as opposed to some other kind of problem?