I wonder if this bug has anything to do with two projects open and exclusive owning or mapping of the particular audio file. I.e. the copy from one project makes a reference to (a portion of) a file of that project and then the second project has trouble opening and seeking to that (portion of) the file during playback. After pasting the clip segment, does the clip inspector property refer to the original file? If so, the two projects are now sharing that file. Interesting that the second project can bounce/freeze the file (i.e. can read it) but couldn't play it. Interesting again that undo of bounce/freeze makes it playable. And this is still with both projects open? Something to try:Select that clip in the new project, then do Track view -> Clips -> Apply trimming, just in case that refreshes whatever internal structure is out of whack.

In addition to the excellent response so far I would double check what driver mode you are using?

ASIO would be the preferred mode but if you are already in this mode it may be worth giving WDM mode a whirl

How many hard drives do you have?  I see the SSD Samsung 840 mentioned above.  Do you have separate drives for your operating system, samples, project data, ect?  I have my operating system on one drive, my Cakewalk projects on a different drive, my sample data, vsti data and backups each on their own drives.   Trying to run everything from one hard drive, can really impede performance.
 
A few things that I've done recently, and it seems to have really helped with those dreaded Audio Engine Stops.
 
1. Installed "Auslogics Disc Defrag"  (for non SSD drives only).  Run this once a week or so, to defrag and optimize my spinning data, and sample drives, to keep them from getting too fragmented, which can slow down performance.  FYI.  I don't have any SSD drives, but from what I've read, it's not good to defrag them.  It can shorten their useful life.
 
2.  Installed Intel's free "Intel Extreme Tuning Utility" software.  (For Intel CPU's only).  This software can be used to benchmark, overclock, and tweak your system, to make sure that you are getting the best performance.  You can even download profiles from other users, and try them on your system.  I was able to bump up performance quite a bit on my system (which is an i7 processor from a few years ago).
https://downloadcenter.intel.com/download/24075/Intel-Extreme-Tuning-Utility-Intel-XTU-
 
3.  Install "Novabench" Benchmarking Software.  Free software can be used to compare your system to others with similar systems.  Helps to see if any of the hardware components are performing below the norms that other users are getting.  https://novabench.com/
 
4.  Make sure that no other audio components in your system are interfering.  I went through Windows Device Manager and disabled all audio drivers which were not needed.  Things like motherboard sound drivers, audio drivers for my 2nd monitor.  Not even sure why those were installed.  If you have ASIO4All installed, uninstall it.  It can be known to interfere with other audio drivers.
 
5.  While in device manager, go through all of the items under the "Universal Serial Bus Controllers" tab.  Double click each one and look for a "Power Management" tab at the top (not all of them have this tab).  Click this and see if "Allow the computer to to turn off to save power" is checked.  If it is, uncheck it.  Windows USB power saving features are cool, but can really screw with DAW performance.  Things like delaying USB drive reads and writes, disconnecting midi controllers when not in use, ect.
 
6.  While you're at it, right click on the windows logo at the bottom left and click "Power Options"  See what power saving plan that windows is using by default.  Usually it's on "Balanced".  I switch mine to "High Performance", to keep Windows from putting system components to sleep, to save power.   I think, that if you install the Intel Tuning Utility mentioned above, you get a few additional Power Plans to choose from.
 
7.  Check your Sonar config file in "Preferences>Audio>Configuration file"   There are several forum threads about changes that may or may not be helpful.   I usually only change "Threadschedulingmodel" to 2.  Supposedly works better for newer processors.  I've tried tweaking other things, but I haven't seen any noticeable difference, so I usually stick with the default for everything else.
 
8.  "CPU Park Control" is a cool CPU software which can help identify if you are getting full use of your CPU.  It's free, might be worth trying that.  https://bitsum.com/parkcontrol/
 
Try some or all of the above.  Maybe something will help. 
 

Hi, to the original OP, are you using the same Template for new projects?
dan

Samsung 840 Evo SSDs had a problem where disk reads slowed down over time. Is your disk an Evo version?
 
http://www.anandtech.com/show/9196/samsung-releases-second-840-evo-fix
 
To fix, install Samsung's Magician software from here:
 
http://www.samsung.com/semiconductor/minisite/ssd/download/tools.html?CID=AFL-hq-mul-0813-11000279
 
This software will also benchmark your drive, and tell you if it's using the right AHCI mode rather than IDE. Mine wasn't, and making the change (which is a bit tricky, so Google it), doubled read and write performance on my SSD.

Hello! Everyone has been incredibly helpful at 
1) providing killer insight and ideas. (thank you!)
2) dealing with the "editorial chaff" which was part of my original post, and likely to continue a tad.
(It's a healing mechanism for me to handle the biting frustration. Tom Brady throws balls to Giselle in his downtime, I have editorial chaff).
 
NEW UPDATE - OFFLINE INSIGHT:
I have responses to ideas below, but new insight is that this is an offline issue as well. I've figured out the following direct correlation when exporting the mix: I'm not able to EXPORT the project when this error appears. I simply get this informative gem of a popup whether I export with or without plugins. If the project file won't play 45% of the way through, the export fails at, from what I can tell, the same spot or 45% of the way through the export.
 

 
MY RESPONSES TO AMAZING FORUM EXPERTS:
Craig: I've tried disabling all other audio drivers aside from Audient including graphics card audio and rebooting. 
Bapu: I could bounce the clips and not freeze, but freezing solves the problem eventually and finds the corrupt audio file. You can come by, however I have to have this working on this computer. :)  I'm in Weho BTW.
Passive Drift: Probably a good idea to restart as it seems to be completely random when it shows up but the dropouts remain in the consistent location, but impractical to quit every time in the long-haul.
arachnaut: tweaked these setting to no avail. Dropout, extraplug, etc.. - but seems to be the same offline
PhilW: You may be correct, but I Loooooooooove the headroom that 32-bit audio provides me. I'd hate to have to switch to 24bit. If it is 32bit it's a bug to be fixed!
BitFlipper: Pasting within Sonar. I import every file, such as a loop to convert to 32bit so I don't have any inconsistent bit rates.
Bvideo: Same problem occurs with just one project.
Boydie: NO WDM option which is way backwards for me anyway
Davec69: My main drive is SSD and the Sonar file drive is SSD. And I have a few other drives with libraries. Kontakt libraries are on a 3rd HDD.  My system is pretty tweaked and I can to to town here, however does the fact that there's corruption give you new insight?  I tried all config file tweaks.  I'm going to dig further into your excellent performance enhancement ideas.
Dan Le: I do use the same template. I'm gonna create a new template going forward, but I have a whole record on this template!! :)
PeterMC: I've used Samsung Magician it in the past and I'll try again. Configuring now.
 
--- More soon.
 
 
 
 
 
 
 
 
 

If copying the project (with audio) to a different folder on the same SSD has no effect, I suggest you try copying it to one of your other drives just to be sure it's not a problem with that particular device.
 
Also, regarding your system being 'pretty tweaked', this could easily be causing/contributing to the problem. In particular, if you've set processor scheduling for best performance of 'Background Services' instead of 'Programs', I suggest you undo that long-ago 'debunked' tweak.
 
Incidentally, thanks for taking my 'editorial chaff' comment in stride. 

<<PhilW: You may be correct, but I Loooooooooove the headroom that 32-bit audio provides me. I'd hate to have to switch to 24bit.>>
 
No matter how good your converters are, you're not even getting 24 bits going in and out of your audio interface, let alone 32. The mix engine and processing is 64-bit inside SONAR, which is where the extra resolution actually matters.
 
I guarantee 32 vs 24 bits would not hold up in a blind A/B test as soon as it becomes analog, because both would give you about 20-22 bits of "real"resolution when you take the noise floor, circuit board layout, and D/A converter trimming inaccuracies into account.

@neonerd re: 32 bit: The headroom of 32 bits that maybe you want is available in Edit->Preferences->File - File Bit Depths [ Render Bit Depth ]. This refers to file-stored bounces, freezes, etc. and can hold hotter or higher resolution signals than you can record, play back, or export to typical devices.

a while ago I was having no end of problems with audio engine stopping and dropouts.
One setting worked for me - MaxThreadCount
you find this in Preferences->configuration File -> properties list 2nd from top

• default is 0 (all cores/threads running)
• Change this to 5 or 4 and see if you still get the same issue ( you have a hexacore - 6 cores/12 threads - so you should restrict to just physical cores. changing to some number above 5 will NOT work ) 

 
Why this may work - Sonar is pretty efficient in thread usage but some devices drivers hold off either cores or threads and this causes drop outs. by restricting Sonar to less than maximum cores, you provide some 'breathing room' for bad device drivers or other sw that is monopolizing a core/thread. 
 
If this does actually work, it is not a total solution, just a workaround while you source this root cause of the issue.
 
Anyway, its super quick to try & very easy to reverse
 
Chuck