Problem with MBP and DVI/OS X Issues

I have a C2D 2.4 8600256mb vram MBP (MBP 4,1) - the Middle of 08 model.

I have a 19" HDTV that I connect to my MBP through DVI - HDMI to watch movies and tv shows on some times. Usually I just mirror the desktop to do it as I only connect it and turn it on to watch movies on.

When I plug it in it usually lags for 3-4 seconds and cycles on and off with a blue background - then its mirrored. Is this normal?

The real issue comes when its plugged in after that though. Everything is REALLY laggy. Moving windows around is laggy, scrolling is laggy, etc. The real issue is when I am playing a video there are "tracking lines" for lack of a better term down the video on my macbook pro lcd panel. The tv doesnt have said tracking lines however. It just seems really glitchy and weird.

I asked the genuis bar folks about it and they claimed it was becuase my graphics card (the nvidia 8600 with 256mb of vram) isnt powerful enough to drive two displays both at 1440x900. This doesn't make any sense however - I know people with mac books even drive two displays. Do you guys think this is a hardware issue? Should I take it back to the genius bar? i dont know what could be done if it is.

thanks so much for any help - forgive the typos I wrote this quite fast

 

Bah, sounds like the "Genius" was just BSing to get me out of there. They do that with me a lot - most of my problems are too technical for them to deal with. Does anyone think this could be a symptom of the faulty 8600s? My card seems fine I think - I play a lot of games on it and it runs OK.