Mac Mini 2009 3,1 Graphics Pausing Stuttering Issue

[afterspark5]

Hi, I was wondering if anyone has experienced strange stuttering issues when using the mini - displayport adapter on a 9400M based mac.

I have a month old mac mini that will pause for about half a second every few seconds whenever doing anything even marginally graphically intensive. All video playback (even low ipod res) under quicktime and vlc stutters this way. Dragging a window around by the mouse stutters this way. A large progress bar (because they oscillate colors) stutters too.

I have two 24 inch BenQ FP241W monitors connected to this mini via miniDP->DVI and miniDVI->DVI adapters. Both run at 1920x1200@60Hz.

I have tried the following to no avail (in this order).
1) Hardware Test from CD
2) All System Updates available
3) Reinstalling Leopard from disks. Even on "erase and install" problem is still present. Even more ridiculous is the fact that the leopard installer progress bar is too graphically intensive and triggers the stuttering.
4) Zapped PRAM and PMU.
5) Replaced system memory with alternate 4GB. I thought this might help since video memory is shared with system memory but no luck.

I had a brief talk with Apple today. They seemed baffled and suggested I zap PRAM and PMU again. They want me to take it to the nearest apple store, but that's 90 miles away, so I'm hesitating a bit.

Any ideas?

Edit: I've put up a couple of movies I've filmed with my macbook pro's isight.

http://shekhar.info/blog/wp-content/.../04/movie1.mov
http://shekhar.info/blog/wp-content/.../04/movie2.mov
In the first movie, the progress bar pauses. In the second, the window really does jump around that much when dragging it around.

[markojug]

I guess your only option is to take it to the Apple Store and get it replaced. Likely a hardware issue. Could be your graphics card.

[Bill Gates]

Did you ever figure out what the problem was? A similar problem just appeared with my 2009 iMac 24" when using the DisplayPort. The whole system stutters for a split second in regular intervals when I have an external display connected but powered off. If I turn the other display on, the stuttering disappears.