Interesting problem I have encountered here. When I attempt to play
any MPEG-based video file, regardless of the playing software used, I
can hear the audio, but no video. At this point I if I go to pause or
stop the playback the current active player window will freeze. After
this freeze, I can open up another type of player and play any
MPEG-based file without any problems as much as I want whenever I want.
This problem is not related to just one type of playing software. For
example: I will attempt to play an AVI in Media Player Classic, get
sound no video, stop playback, then Media Player Classic will lock up.
After it locks I can open up whatever I wanted to view in Windows Media
Player and it will playback without any problems at all. In
retrospect, if I were to start playback in Windows Media Player first,
it would be the program that locks, then I would be able to view
whatever I wanted in Media Player Classic. I've tested this with the
Divx Player 6, WMP10 Media Player Classic 6, Real Player 10. And the
symptoms follow each of these programs. Not sure if I'm dealing with a
codec issue on this one or not considering I can actually achieve
successful playback, but at the price of fowling up another player
temporarily to do so. I do not encounter this problem with other video
types (mov, rm, etc). Only seems to occur with AVI, WMV, MPEG-based
formats. As a last note, when I attempt to close the player that
encounters the hang, my system will hard lock causing to me have to
kill the power and start over from a cold boot.

System specs are as follows:

Windows XP Professional
AMD Athlon XP 1700+ (~1.5ghz)
512MB DDR PC2700
ATI Radeon 9000 64mb (latest driver)
80GB Hard Drive
DirectX 9.0c

Just an update, still suffering with this problem. Just completed a
reload and still coming up with the same problem?? However, I can play
anything I want in Quicktime without any crashes or hangs at all. The
only problem with that is certain AVI/MPEG files are not supported and
sometimes the audio is garbled. Oh well, still lost and looking for
another opinion.

Finally! The problem was with the latest video driver I was using for
my ATI Radeon 9000 card, I downgraded the drivers to one of the
previous versions and was able to play all video files in whatever I
want without any crashes.