I've been using Vegas 9.0 without any problems for a few months; audio and video were fine and I've rendered plenty of short files that work perfectly.
Today I upgraded to 9.0e and since then I've hit a problem with audio. It has a very stable 'stutter' that isn't related to any sort of hardware constraints (as in, I don't think it's related to CPU load) because it's so clearly stable and structured. I've attached a screenshot to try and explain it, but essentially the audio drops out for exactly 9 frames (at 59.94 fps) then plays for 24 frames and then drops out again - this happens consistently right the way across the entire clip.
The input files are .mp4 captured from a Samsung H100. It used to work just fine until the upgrade. Files that I have previously rendered (also into .mp4) import without these audio drop-outs.
Has anyone seen this before? Does anyone have a workaround? I've tried multiple ways of importing the clip but I can't make it work correctly.