*** UPDATE:  Hang Dump Provided in Post #12 ***
 
Gents,
 
I'm running a newly rebuilt 32 bit DAW with RME FF400, Sonar 5.2 PE and WinXP (yes, I realize the versions are old) and I'm experiencing random lockups in Sonar that appear somehow related to recording being enabled, often after recording.  I get the Windows hour glass and Sonar stays hung that way, leaving me to kill Sonar with Task Manager.  I've tried the obvious like buffers, picture cache, etc. no change.  HOWEVER, I did find something very interesting which I now believe is major evidence the problem is within Sonar and am hoping somebody on the forum might know what is happening...

I looked in the Audio Data folder and there is always a file after every crash that is NOT one I recorded.  It is usually time stamped shortly after the most recent take, and the naming convention differs.  The sequence looks like this:
 
SonarAudioTest, Rec(762)                                 4KB           12/19/2017     12:52pm
SonarAudioTest, Guitar Left, Rec(758)      1900KB     12/19/2017     12:44pm
 
The 2nd file is the take I recorded, but the first one I have no idea what it is - seems Sonar created it on it's own, and that is right when Sonar hung.   The file is a type WAV - but not valid according to other software.
 
Any experts on the forum know what is happening here?  The answer to the lock-ups likely lies in the above evidence.   
 
      Sonic

That file is created when you allow record arming during playback/record (I forget the preferences setting though).

KPerry
That file is created when you allow record arming during playback/record (I forget the preferences setting though).

 
You're right, I see how the file is created on start of playback and then erased when stopped.  I wonder though if that file I/O (creating and deleting) is what is causing trouble somehow.  I looked around and couldn't find that preference setting.  
 
I have no idea why the system is doing this, 10+ years and never had a problem until I rebuilt this new DAW. Besides the motherboard (Intel Dual Core P), the only difference is W2K vs. XP and a PCI vs. PCIe firewire card.  Everything else, all software, drivers and external hardware are identical.  But for some reason once I have a track armed Sonar decides to randomly lock up.  Even sometimes when I'm not even playing or recording.  Memory is fine too, so it's not a resource problem.  No other symptoms or problems with any other software in the box as far as I can tell either.
 
I predict low probability of finding the cause on my own without some help from the experts on the forum.  I've tried almost everything I can think of at this point...   Last thing I'm now attempting is turning off the multi-processor setting inside Sonar as well as the 64-bit mix engine.   
 
Sonic

Well, that didn't work, even with multi-processor and 64-bit mix engine options disabled still locked up.   Hmmmm..... what about MaxPlugInBufSizeKB or ExtraPluginBufs in Aud.ini?  Any chance that might be it, not set high enough??  Presently set to 128 and 0.  
 
Sonic

Are you sure nothing else is trying to access that folder?
 
I had a heap of problems with OneDrive trying to sync my audio folder whilst I was recording to it. Once I disabled OneDrive, the problems went away.
 
This folder should also be excluded from any virus checkers.

Well, changing those buffer settings didn't work.
 
Yeah, as far as I know nothing else accessing the audio folder.  It's just a pure DAW, no virus scanning, no network connection, no non-audio software installed.
 
One thing I'm noticing is every time I stop playback/recording there is a pop sound.  It is registering on the RME Fireface 400 Out1 LED on the front panel.  Even if I mute all the tracks, still that pop. Strange because nothing ever caused that Out1 LED to blink before best I recall. I wonder if that has anything to do with the problem.
 
Am also wondering, could the problem be video driver related somehow?  I'm simply stumped.   When the hang occurs the processor readout in task manager sticks at about 50% usage and both cores are processing away on something.  But Sonar never returns, Windows hourglass forever.
 
Sonic

I've been having Sonar hang on me for the past couple of weeks. I put it down to a Windows 10 update, but I switched to my Window 7 boot and it started doing the same.
 
I only noticed today that Cakewalk Analytics is still enabled - which I assumed was doing nothing, but maybe it's trying to communicate with a dead server and hanging Sonar?
 
Anyhow I've turned it off - too early to tell if it's fixed the problem, but might be worth a shot.

SonicExplorer: Have you tried what KPerry talked about? That setting definitely changes the way Sonar accesses the audio drivers when starting and stopping the transport. Two clues lead up to it: the popping noise and the extra file.
 
Edit > Preferences > Project - Record  uncheck [] Allow Arm Changes During Playback/Record

You mentioned a PCI vs a PCIe FireWire Card. If that was part of your recent change then that’s a likely culprit if your motherboard also has PCIe slots.

In those boards the PCI slot is emulated and is not very reliable or stable. Known to cause problems just like you describe. Also the chipset on the FireWire Card is critical for stability. Usually a Texas Instruments one is recommended.

Guys, many thanks for hanging with me.   I will try unchecking the "allow arm changes during playback" option as soon as I finish the current testing and report back.  Right now am running a few other trials such as putting PFSendMute back to 0 (that was the only manual change I made to Aud.ini).  Also increased MIDI buffers in case it is related to the drum DXi. 
 
A bit tedious testing since I do not have a specific method to reliably reproduce the hang.
 
BTW, I am running a PCIe firewire card with a TI chipset.
 
Sonic