Ok, I ripped out all the plugs and still Sonar hangs.  The only thing I have left is ONE DXi wrapped in Directixer (Superior Drummer).  Fails with either Superior 1 or Superior 2 so I don't think the DXi is the issue, unless it is the wrapper (Directixer) that is responsible.  But I have no safe/easy way to eliminate that variable at the moment.
 
I'm going to next try a painful start/stop test sequence but not moving the mouse away from the focus of the area where the transport buttons are and see if that makes a difference.
 
I'm also a bit suspect about MIDIYoke being loaded, even though it's not being used, so to speak.  Not sure if maybe I should risk trying to disable it in the devices view.
 
Yes, I have separate OS and Audio disk, always ran that way before no problem.  But that was on a W2K single-CPU/core system.   
 
I just compared another hang dump and it's darn near identical, whatever is happening is the same thing, at least that much is encouraging - meaning it is indeed ONE CONSISTENT problem.
 
I could re-locate the audio disk drive onto the same Primary IDE Channel as the OS drive as long as it isn't going to confuse Windows and end up muck something up in a domino effect.  IIRC my thinking was to make use of separate IDE Channels to reduce any potential conflicts or the two disks competing for use of the same IDE Channel.  Keep in mind, I'm using SATA drives, however the BIOS is configured to run in IDE legacy mode, on purpose so I don't have to mess around with SATA drivers, slip-stream, etc.  System is blazing fast for my needs so I'm not remotely concerned about hypothetical speed limitations compared to running in true SATA mode.
 
Sonic

Okay, I just reread your edited post. You have SATA drives running in IDE legacy mode (set in the BIOS). Make sure your mobo has the right chipset drivers installed.

Ugh...too early to be sure since more testing is needed tomorrow, but it seems as if there is some dynamic involving Directixer.  I turned on the Fixed Buffer option for Superior Drummer inside Directixer and as of yet haven't been able to get Sonar to hang.  BUT now the machine freaks out when I have other things in the Synth Rack - and sometimes even when I don't.  CPU goes red and massive popping and sometimes screeching.  And can't even get it to stop by disengaging items in the Synth Rack, have to close the whole project. I just can't imagine what is the root cause of all this lunacy.  I still go back to the fact it feels like some kind of quirk related to incompatibility between XP SP3 and the other DAW software because none of this baloney happened on W2K SP4.
 
 
 

Red herring, the Fixed Buffer setting in Directixer causes havoc and hangs as well.
 
The hang only occurs after stopping, not when starting, not while playing/recording, not while editing.  What is it about stopping the friggin' transport that is so special it could be the root of all this ?!
 
Anyone ??
 
I may have to buy another disk (was thinking about doing that anyway as a backup) and make an image duplicate so I can try more extreme theories/troubleshooting without risk to the current disk.
 
 

Going to a newer OS is not the answer, in 2 or 3 years the same paradigm will just repeat itself and there will be people saying to upgrade again.  There's absolutely nothing conceptually wrong with an W2K/XP box and slew of software designed to run on it. All of which I already know well and own, along with all the compatible hardware and drivers. Which I can keep running and servicing for many, many years to come.   There's just one maddening intermittent quirk hiding someplace in this new DAW that needs to be figured out.

I was pondering testing the Superior 2 Drummer VSTi using the cakewalk VST Adapter in S5 instead of using Directixer......but I'm not sure what will happen.... can VST's that are wrapped by Sonar VST adapter be completely "removed" using the plug-in manager? Or rather once they are scanned & added does Sonar basically have them permanently installed in the OS somehow?  Asked another way, is this something I could test and easily "undo" or would I end up committed somehow with Sonar or the OS and not be able to easily get back to where I started??     Previously this was not a potential solution because the VST adapter had issues with mono tracks, but with Superior 2 Drummer they are all stereo, so if I was able to get around the hang problem that way, it might be a viable workaround to live with.  And if Sonar still hangs then I will have at least eliminated another major possible culprit (Directixer).
 
Sonic
 

Is your CPU multicore? In those days of Sonar, there were not so many DAWs running multiprocessor. There were combinations of Sonar w/ some asio device drivers that that had problems, likely race conditions between threads. These were only resolved in later years.  A way to test for this is to set the CPU affinity for Sonar to just one CPU and see if your hangs go away.

Yes I am running a dual core Pentium.  I too suspect there could be a race condition or bad programming, not supporting multi-core correctly.  I did already try turning off the "Use Multi Processor" option inside Sonar (or whatever it is called), no improvement.   But, I also read in the manual that turning that off does not stop multi-processor operations for everything, so even when off it might still be causing the problem, no way to tell for certain.
 
@Abacab, are you saying I could get a Win7 or Win10 box and run a vitalization mode where XP could run and all my software as well?   I considered this initially but somebody told me the chances of an XP DAW setup, and firewire hardware of that era all working within a virtual machine would be very unlikely.  ???
 
One final maneuver I may try is to put Superior 2 Drummer in the Sonar VST Adapter and see if the system still hangs.  i just hope it is fully reversible if the test doesn't work rather than borking up my system permanently further.
 
 
 
 

THAT MIGHT BE THE SOLUTION, THANKS !!!    I KNEW the hang was possibly multi-core/processor related and managed to narrow things down to a few potential culprits - but after failing to achieve single core mode via the Sonar settings it never occurred to me to set the process affinity to force Sonar into single core mode.  I have been beating on the machine for over an hour and no hang.   I will continue testing tomorrow....
 
If this fixes the issue, how do I manage to make this setting perstst as desired?   I did a quick search and there aren't many solutions.  Apparently there is no way to launch a program with a certain affinity setting/switche?  That is just crazy....  
 
Anyway, if the theory holds, then it also adds credence to my other hypothesis that by using Superior Drummer inside of the VST Adapter rather than Directixer it may fix the issue as well.   The more broad, transparent and portable solution however is to seek out a way to be able to adjust the affinity of the Sonar process so it launches as desired.
 
Sonic
 
 

Studio-ES
You can create a custom shortcut to Sonar.exe in cmd prompt which specifies which CPU it should run on. Google it.
How does Sonar run on 1 CPU? I'm glad you're getting this sorted, thanks to bvideo!

Sonar runs fine on 1 core but obviously I'd like to stay with two.  For example, in a basic rock song at the moment, still missing vocal, is using about 17% with both cores. With one core it uses about 27%.   Almost mix ready, so most plugs are already in place.    I'd probably get near 50% or a little beyond after vocals and mix prep, but that should still be fine.
 

Well, if indeed this theory holds true then issue is caused by one of just of a few suspect components, but I hope it isn't the drivers.  RME drivers have always had a great reputation, would be really disappointing if that's where the problem lie.  But dated 2007, maybe they didn't yet have support.  I rather suspect it is either in the particular VST wrapper I'm using or in the drum synth.  The only other place it could be is within Sonar, and that is highly unlikely since the bakers obviously understood multi-processor software design by the mere nature of having a multiprocessing engine all the way back as far as S4 was it? (Plus I would think a LOT of Sonar users have been screaming for years all the way through S7 had there been some design flaw).  So yeah, the list is very short on the potential culprits....