I have an application that was written to be compatible with DirectX 3 (originally for NT4 compatibility). This application streams music to a 2 second DirectSound buffer. I use notification events on non-NT4 systems to signal when the write cursor has passed the middle and end of the buffer, writing to the opposite end of the buffer each time. This works fine on most systems, however, on some systems I get bad stuttering and choppy playback. In fact the playback sounds more like it is being corrupted rather than my application being too slow to update the buffer. It works fine here on this P4 with a SoundBlaster PCI on W2K, yet it stutters on my P4 with a SB Audigy under XP. There are similar W2K machines here with different sound cards that also stutter. As a guess, I modified the Windows sound acceleration levels to no acceleration (one notch above nothing/emulated) and *presto* it plays fine on problematic systems. Any higher acceleration settings and the stuttering returns. I then did some searches on the net and found that this is a problem others have encountered. However, although all these sites suggest adjusting the acceleration level to solve the problem... none of these sites ever mentioned WHY the stuttering and choppiness was occuring with acceleration enabled on these systems. Some blamed problematic video cards that locked the PCI bus too long, but I don''t think this is the case on all the systems I''ve tested on. Obviously other games and applications can stream to DirectSound buffers smoothly, so what can I do differently to make it work with acceleration enabled? Asking the user to disable acceleration is an extremely poor solution. Streaming is not a complicated process... I can''t see what I can do differently. I''ve tried increasing and decreasing the buffer size to no avail. Any ideas?!?