Picard 256 I have had this issue before on previous versions of powerdvd ultra. It happened when in two different instances. One if you're running anything running under windows 8, you have windows aero turned off, playing back videos shoots up the brightness and contrast super bright.
The other instance if you are running powerdvd in the windows media center it seems like it disables windows aero and then it happens again.
So basically I now run it in normal desktop mode and don't have any issues.