I do a lot of video editing, and ever since about a year back, I have NOT been able to playback a DV quality, or even relatively high quality movie smoothly. I have analyzed my CPU usage, and as soon as I play a movie my CPU usage shoots up to 100% and the frame rate dies to about 3 FPS.

I have a DELL Dimension 8300 with 2 GB RAM and a 3.2GHz Pentium 4. I have a ATI RADEON 9800 Series. I'm running dual flat panel monitors. I have Windows XP Pro. I've thoroughly cleaned my startup programs, and get the same 100% usage when I run the video without ANY applications running. I also get the same result in all players, Windows Media, Winamp, etc. It seems to only be with high quality DV video, lower bitrate video plays fine.

To my knowledge, I have the most recent ATI drivers installed. My memory usage is virtually 0% when I run video, but the CPU goes crazy. Can anyone offer some advice? This is a very important issue for me to resolve.

I had that problem awhile back (some time ago) and I think what I did was set the priority low on WMP and it worked fine. That might be worth a try.
Open windows task manager and right click on wmp and you can set it. If that doesn't help, you can always reset it to where it was.

Hopefully my advice will help you...Please post back with your results....thanks

Unfortunately that didn't do it. Any other possible solutions? Some have suggested it might be a codec conflict...?

maybe someone else has a solution for this?

Hopefully my advice will help you...Please post back with your results....thanks