I just installed suse 11.1 kde 4.1 version. The problem is that when I open a video file the player instantly closes. This is valid with all the video players. This happens when kde effects or compiz effects are enabled. When the effects are disabled everything works fine. This is not a codec problem, because all the codecs are installed. I have an ati x1200 video card.
start a player from a terminal
eg: in a terminal type
see if it outputs any errors, I guess it will not, because you imply it happens when you play a file. So maybe the program will open fine.
You could try changing the the settings for video output in the player itself.