New monitor but wont play video now

Hey ppl while since i last posted but need some help.

I bought a new monitor today and linked it up to my rig. I got a 9800gx2 gpu and went from a 17inch monitor to a 22 inch monitor.

The only problem im having is when i open a video file i only get the audio with a black screen within my media player. I've tried changing the desktop reolution and have the latest drivers. I havent yet openeded the monitor manual though. Also i swapped from using two VGA adapters to using DVI. When i open Nvidia control panel and go to 'adjust image settings with preview' the image that is supposed to be there rotating is replaced by squares and lines.
I have tried using VLC media player and WMP with no change.

Any help is much appreciated thnx.

Install the a driver for you monitor then see what happens. I've never seen this type of thing caused by the monitor but you should install a driver for it.

Okay im not sure what caused this problem but i installed the driver and the software which came with the monitor. This didnt fix the problem. I was running a dual power corde split between my pc and monitor. I gave the monitor its own power corde and plugged it in. I then put an VGA adapter onto the monitor input, turned the pc on and suddenly its working.

I would still like to know why my pc doesnt like DVI input into the monitor though or if it was the power cable i swapped?
Thx

try reinstalling the drivers for the 9800gx2 gpu, the monitor should work without drivers, altjough it will work better with the correct drivers.