I've recently been having problems with video playback in MC. I've mentioned it in a few threads, and described it in detail (
here,
here, and probably a few older posts that I didn't bother to find), but the basic gist is this...
I'm playing back an AVI file (it turned out in my case that they were all XviD/DivX encoded files). The files live on a network drive, though the network is stable. Periodically, playback would freeze and MC would hang (and I would have to kill it via Task Manager). If I waited patiently (or as soon as I killed MC via task manager) within a few minutes, MC would come back to life and would throw it's "Couldn't play any of the files in the playlist" error, and then Windows would report that my network drive had gone offline. I was able to reconnect to the drive immediately though.
This led me to believe that my network was being a little flaky and was dropping packets here and there, which confused MC. I replaced everything in my network. All of the network cards, the switch, all the cabling, I built a new IPCop firewall/router. I was planning to do all of this anyway, but nothing helped...
So, I became convinced that it was MC and started testing. While MC was frozen (before it came back to life) I was able to access files on the drive (using another player of course) and ping the remote machine with no problems. In fact, I tested it by running a continuous ping on the remote machine and played back a file, waited till it froze, and checked the ping progress. None were dropped. I tested playback in WiMP, Quicktime Pro, and Media Player Classic and none of them were reacting in the same way, though I did notice occasional "hiccups" in the video (which is probably when MC was freezing).
Since I noticed the hiccups, I started to consider other possibilities. It was then that I figured out (through about 12 hours of exhaustive testing) that it was only XviD/DivX encoded files (and not MPEG-1/2 or Quicktime-created MP4 files).
It turned out that it was my XviD codec. I don't know how, but somehow XviD had usurped playback of my XviD/DivX encoded files from ffdshow, and I was running an older build of XviD. I downloaded and updated all of my codecs (using the incredibly helpful
Gordian Knot codec pack) and the problem disappeared. I hesitated to post this, because I've been faked out before and had the problem resurface, but it's been fine for about a week now, and I really think it's solved...
The moral of the story is... Check your plugins
and your codecs!