Well, im having the same problems, though i wasnt really going to nag about it.
The sollutions that have been offered so far didnt seem to change anything, but i havent had the time to devote an afternoon to the subject.
My MPC version is 6.4.9.0.
To answer you question Jude, I check this thread every day. Hoping to find new content that may not be in .rm format, or maybe hoping somebody converted the posted content to .mpg or .avi, or for a solution for the codec hell.
The content seems absolutely exellent, so keep it up!
