Why, oh why, can't technology be simple?

I bought a new widescreen monitor yesterday because I was at the limit of my patience with editing photos on a laptop screen! The maximum resolution on the laptop is 1366x768. Maximum resolution on the new monitor is 1920x1080. Fabulous!

Now, here's the problem - if I set the monitor to full resolution, it doesn't use the full screen - there's a black band around the edge of the screen where my cursor refuses to go! Same at the next step down (1776x1000), but if I set it to the next step down again (1680x1050), the full number of pixels are used - but the display is slightly stretched horizontally (and plus everything looks "huge"!).

So - how do I get it to use the full set of pixels? Has anybody else had this problem and resolved it?

If it matters: laptop is an HP Pavilion, monitor is a Toshiba Tekbright PA3769 (no CD supplied). OS is Windows 7, 32 bit. The monitor is set as the secondary display, to the left of the laptop. I've tried updating drivers, including my graphics controller, all to no avail!