i've given up
with my last 2 pc's including current, i installed the K-Lite Codec Pack and while obviously the wmp does play more content, it does however cause the wmp to crash when playing certain .avi files, and then the system has a hissy fit and the folder in which the avi clip was stored also crashes and dissappears.
And since , the wmp will not play in Full Screen for any movie format..it will go to full screen for 2 or 3 sec but only with the original movie size at the top left, and then it will either revert back or crash altogether

I re-installed wmp with no luck, so the prob lies deeper
As i am not cluey enough to tinker around with the registry(even though you can do a 'System Restore' if you fuk up, i don't have the patience), i now use vlc which plays everything, including broken avi clips and i am more than happy with this little gem
But I always keep thinking back if i installed one too many codecs and are now conflicting.. i have nfi