Video player graphics problem

I have an issue on my pc where all my dvd / avi playing software, such as divx, powerdvd etc open up videos and plays them with a black screen, this is rectified by opening my Nvidia control panel, as soon as i open it the video shows in all its glory!
It is strange because i dont have the problem when i use windows media player.
Also, it only has happened since i updated to the latest Nvidia drivers, but i have tried rolling back the drivers and it does not help!

AMD 64 fx-53 @ 2.4ghz~
GeForce 6800 ultra
2 gig ram
Windows XP home

Anyone help?