my sugestion:
leave wmp9, real and qtime as they are used in internet pages - streaming media formats...
use mpc as test player cause it has lots of built in codecs so u can check is it file or system problem .... (i also use mplayer from
www.mplayerhq.hu as a test player ) (also graphedit helps to see what directshow filters are used on playback)....
and of course bsplayer as a everyday player ...
some hints:
if u keep realplayer and register realsplitter.ax (search for gabest and realsplitter.ax - it's on
www.sourceforge.org ) u can watch realmedia files with bsplayer (local playback only)... for quick time there is no solution i think (at least working one)...
some experience:
i never installed wmp9 caouse of its slow loading and not so many features.... stick with wmp 6.4 if u can...