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.

I'm an old timer myself, and I like to keep old systems running as long as possible.  I have built most of my systems for the past 20 years.  But there is a point of diminishing returns, and wasted time and effort at some point.  Not to mention nearly impossible to find spare parts, like good AGP video adapters.
 
So there comes a time when I have to cut loose with the old stuff and move on.  I still have some perfectly good single core Pentium 4 motherboards, CPU's, and RAM that run XP very well, but have outlived their usefulness.
 
The longer you hold back the more you will be all on your own for support as well.  Even guys like me have forgotten much of how to make that old stuff work by now.
 
I installed a Windows XP 32-bit system in a Virtual Machine on my Windows 10 Pro 64-bit box, just so I could open older 32-bit applications that will not install on Windows 10.  I have Sonar 6 and 8.5 working on that.  It's a good way to access legacy files and such, and even open older files to convert them etc. I have over $1000 in software that did not make the trip over to Windows 10.  Sucks, but that is life.
 
Hang in there, and if you eventually decide to catch up, there are folks here willing to help.
 
However, I will say that running a DAW on modern PC hardware is like the best thing ever! 

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.
 
 
 
 

I tried turning off "Use Multi Processor" when I had multiprocessor issues in 2006 (Sonar 6 and XP). No help. But using Windows (CPU affinity) to set Sonar to have only one CPU did fix those problems.

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
 
 

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!

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.
 

One CPU was how I ran until Sonar 7.0.3 and the ASIO drivers for my device were fixed. Tragic.

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....

Update:  Ok, so RME confirmed there's never been any multicore/multi-cpu issues with their drivers, which is not surprising since  the RME drivers are some of the most solid pieces of software I've encountered.
 
So after a few more hours of stress testing I remain unable to get Sonar to hang with the affinity set to 1 processor/core. Whoohoo!   Interestingly though, if I leave the Multiprocessor option checked inside Sonar I do encounter some occasional weirdness but that's to be expected I would think.  As long as I uncheck that option, which is the logical thing to do with the affinity set to 1 processor, then everything seems to function fine.
 
The next (and probably final) test is to put the Superior Drummer VSTi into the Sonar VST adapter (instead of using Directixer) and see if that works in a multi-processing environment or rather if it too hangs.  Before that I should probably get another disk and make sure i have a working image transferred & functioning in case something goes unexpected during testing.   And in the mean time I also need to figure out ways to make Sonar start up with the custom affinity setting.  There's isn't a tool in XP to do this.  Ugh.  (The "Start" CMD shell tool in XP didn't yet have the /affinity switch in it)
 
So ..... I'll sign off for now until I have further information to share.  But I will update again at some point to make sure this thread eventually has a proper conclusion.
 
Many thanks to the awesome members on the forum who always seem to inevitably find some way to help others solve their problems.
  
Sonic