playback stops for no reason on correctly configured system

[what is it?]

Here we go round the "AA stops" tree again...

Like several others on the forum, I still have intermittent problems with recording just stopping cold for no apparent reason.  I am also having this problem, again intermittently, with simple playback.  I have read various threads and have carefully verified the following:

- ASIO driver not set to be released in background

- Context menu on the Play button set to Play from Cursor to End of View (or End of File - same behavior)

- Lots of free space on my primary and secondary AA temp directories - primary is NOT on the same drive as the OS

- ASIO buffer size set to 6 msec, 24-bit samples

- WAV cache size in Preferences|System set to 128 mb

- System resources - Memory has plenty of headroom (I have 2 gb physical of which 500+ mb is free at all times) and CPU is moderate at about 40% with no sharp spikes (I have a dual-core 2.1 ghz processor and the behavior manifests itself in both single and dual core modes)

- All possibly offensive background processes such as antivirus, anti-spyware, Windows Update manager, screen saver, etc. are disabled - this machine is kept off the web so none of that stuff is used

- Video card driver set to nonaccelerated mode

- Hard drive is defragged

- Hard drive performance options set to high performance (meaning the drives hardly ever stop spinning)

I am recording and/or playing back three to four tracks of audio - seemingly not enough to cause AA to break a sweat.

So....what is it?  If I am forgetting to look under some rock, please tell me where else to look.  If it is just a bug, let's all face up to it and figure out a workaround or patch.  It's damned annoying and a real hindrance to productivity with an otherwise fantastic tool.  I am at my wits end!!  Thanks in advance and a special place in heaven for the hero who can solve this puzzle.

Since the crowd seems to be as stumped as I am, I am cross-posting on the Adobe forum but would still welcome any and all ideas here.  I will cross-post the solution to the Adobe thread if one is proposed.