Have you tryed to see if there is any download drivers for the PC to correct this problem.
some times they have other resolutions with a newer driver that will be optimized for an HDTV.
In the past few weeks I purchased a new laptop (HP dv9000 running Vista x64 Home Premium SP 1) with a HDMI output. Today I tried to hook the laptop to my plasma TV via a HDMI cable and it looks and sounds great except that the edge around my desktop does not display on my plasma TV. I've tried adjusting screen resolutions, mirroring the display, and making the external plasma the only display. Nothing fixes the problem--even at the super low resolutions the cropping is seen.
My graphics card is an NVIDIA GeForce 8600M GS. By default I run at 1440 x 900 pixels. I have a SAMSUNG HP-S5053 and have played with all the menu settings and it doesn't seem to allow you to move the picture if you use the HDMI input vice the PC input (the option is grayed out). The number of pixels on the HP-S5053 is 1366 x 768 so I wouldn't expect my highest resolution to show entirely, but I do expect the lower resolutions to display completely without the cropping effect.
I have a 17" laptop display and about 1 cm of the edge is the area that is cropped on my plasma TV. I can work around this, but it is annoying. I'm hoping that someone can point me in the right direction. In poking around on the net it appears I might be encountering an overscan problem, but I've yet to find an answer.