Thanks for your suggestions! 1) It's old but not OLD. It's XP Pro 32-bit, 1 GB RAM, AMD64 dual core 3800, Radeon X1800. All of my emulation and Gameex is running from an external USB 2.0 hard drive, separate to the OS. Output is S-Video to a TV at 1024x768, 32-bit colour 2) Following a codec cleanup procedure in this thread http://www.gameex.info/forums/index.php?showtopic=5994 , I cleaned out all codecs and installed FFDShow, Matroska, and Quicktime Alternative. There may be residuals left over from a codec pack, but I haven't had any video problems but for this. A clean OS install would be too much for such a small problem which it may not even fix, and I'm happy with the way everything works. 3) Yes it plays correctly in WMP Classic. I'd like to see if Onji says something similar.