Problems with games since new tv??

Bought a new tv last weekend and hooked it upto my machine via a dvi-hdmi cable through the specific hdmi/dvi input on the tv. Whilst everything else works perfectly (browsing, general pc usage, wmp/media center etc) I find games keep jerking, as if the hardware is struggling, things run smoothly for a minute or so then things freeze etc and then resume for another few minutes.

This happens across the board with every single game i own, old or new and happens regardless of what settings i use ingame, ie.lower resolution, turn off AA etc. Also not just the graphics stutter but sound also, even when again turning those settings down in game.

Since I use a set of 5.1 speakers for the pc i tried disabling the HD sound output on my gpu with still no difference to anything, i've also tried putting the catalyst control settings back to default and again no joy.

Anyone that can offer some ideas would be greatly appreciated, as said before everything apart from games runs perfectly smoothly using full settings on my gpu and the tv's native 1360x768 resolution, and everything including games used to run perfectly before using my old vga monitor and still does if i reconnect.

Machine specs are:
AMD athlon 64 x2 6000+
4gig ram
HIS ati radeon HD4850 1gig
windows vista premium
samsung 50" plasma via hdmi/dvi

did you try playing with the resolution on the tv? maybe lower it a little and see what happens. and check your refresh rate on your gpu.

yeh, like, maybe your refresh rate is set to 24hz, when it should be at 60 hz.

I had a similar problem with my setup. The Nvidia kept auto detecting the refresh rate to 61 Hz instead of 60. When I manually set it to 60, all was well.

Do you have a model number for the TV?