I have downloaded quite a few

.avi and .mpg files

but every so often windows media player can't play them
claiming that

"class not registered"?

the microsoft help pages are not forthcoming with info on this
problem.
trying to play the same files with real media player also does not
work. there is no clear error message from rmp, though.

why do these files that people are sharing on gnutella do not
work for some?

can someone help out here?
best, s

tech details
i run win98se
winmediaplayer 9
realplayer10