I'm going to let the machine sit next time for an hour and see if it ever recovers. Haven't tried that yet.
What about Windows DEP? Should I turn that on for all processes and see if maybe it catches something? Kind of nervous about enabling that, never messed with it before, no idea what side effects it may introduce.
Also, what about the "Arm For Recording" feature in Sonar (or whatever it is called)? I don't see anywhere in S5 it can be configured, but I was thinking maybe when a track starts or stops playing a lockup could be related to that feature creating/deleting the file that is associated with the feature (allowing the enabling of recording while already playing) Probably didn't describe that too well, but hopefully you guys know what i'm referring to. Sonar creates, then cleans up, a file in the audio directory every time a start/stop sequence occurs. I suppose if the creation or deletion of that file went wrong during a start/stop operation, it could cause Sonar to hang.
My gut is telling me this is either a sound or video card issue WRT the motherboard (collision) or SP3 is at fault (should have stayed at SP2 where the file dates and RTL's pre-date Sonar). Could well be that Microsoft made changes to RTL's that aren't playing right with drivers or Sonar or Plugs that pre-dated SP3. Wouldn't you know I erased the SP2 uninstall so I can't even reverse it now. Ugh. It maybe could be an audio hard drive problem I suppose as well, maybe the drive is not responding to an I/O request. I wish there was some way to troubleshoot the system once Sonar hangs, to figure out WHERE it is hung, even in a general sense that would make a huge difference in figuring out what area to narrow the sleuthing.
*** UPDATE ***
PROBLEM IDENTIFIED:
The issue is related to multi-processor (core) operation. There is a component (I believe Directixer) that is not playing well on a multi-processor machine. When I force Sonar to run in single-processor mode, no problems.