unfortunately there doesn’t seem to be any common factor in terms of hardware or setup, it’s just a tiny percentage of players are encountering this, and neither me or valve know why yet, but if you could email me at cliff AT positech dot co dot uk, I’ll ask valve to contact you as well. It’s much appreciated.
I received an e-mail from Valve earlier this week, and when I got a chance to reply to it I was unable to reproduce the fault. This leaves the question, has the issue been fixed with the patch steam downloaded yesterday?
I sincerely hope it has, and initial reports are that yes, it has been fixed.
In which case it was a bug in the third party sound library, and not ym code at all.
I rock! 
I’ve been getting the same issue trying to play the demo version downloaded directly from the website (No STEAM) - it looks pretty good, but with the constant hanging it’s totally unplayable 
I’m using a Samsung Chronos 7 Gamer laptop running Windows 8 - the game fails to run at all under standard windows 8, but seems to run with XP (Service Pack 3) or Windows 7 compatibility turned on - except for this stuttering/hang problem…
Graphics card is NVIDIA GeForce GT 650M