This applies to all video files and is not specific to one video player either (none work).
After changing screen resolution the videos will start playing but the picture will be black with the occational red green or blue colour appearing. Sound playback is not affected.
I have the most recent video drivers installed and all the videos work normally before a resolution change.
This never used to happen and i cannot seem to pinpoint what casued the change and how i can fix it, i would be very grateful for any help.