Tearing via DVI Out

Basically, ive just invested in a really nice 37 inch dell hi def tv, and have my laptop hooked to it via DVI output.
My lappy is running a 6800GO with 256mb video memory, the latest bios as far as im aware and quite possibly the latest drivers.

Anyway most of the time things are fine its just when i play back a video, there are tears in the picture. This doesnt happen all the time just in certain parts, i dont think its the tv the response is 12 or 16ms i believe but i dont see any ghosting and i dont think a response time issue if it was, would cause tearing?

Ive even got Vertical Sync turned on in the control panel to no avail. the only thing i can think of is im using modded infs to install the latest forceware driver off laptopvideo2go or something onto my mobile 6800.

Anyone got any ideas? Could it be the dvi cable at all? i have no idea, but th etearing only seems to be in videos :(

My guess is just that it's not powerful enough - what is your CPU?

Maybe try changing the refresh rate? Also try some different video players - that chip might just have hardware acceleration for HD content which would help if you had the right software.