I've bought 2 DM500s that both slowly loses video and audio synchornization (the audio runs slightly faster than the video playback). I checked with another friend who also has a DM500 and it has the same problem. Several people on the forums have also had this problem.

The only way to solve it is to disable "fast zapping". But with zapping disabled it takes 3 to 6 seconds for the video to be displayed. I have tried several emulators and firmware images with no success. It appears that this may be a problem with the mpeg deconder, which is responsible for mantaining video/audio sync.