LabVIEW 2014 x64 AppCrash StackHash crash

Question

Our application is crashing somewhat inconsistently in the x64 compile, but not the x32 compile.  We are using LabVIEW 2014.  When it crashes, LabVIEW stops responding and has to be closed from windows.  The View Details feature says it's AppCrash and further says StackHash_someHEXnumber.   Another member of the team analyzed dump files and seemed to think it's crashing in the LabVIEW run time.  
Any known issues out there that would explain this?  
It happens on the original release of LV2014x64 and SP1.  It happens in LabVIEW and in a compiled executable.  If is not consistent, if we open the software and start running tests, sometimes it will never crash, other times it will crash before 1500 test runs.  Our way of testing this has been to run 1500 runs, then close it then reopen it, run again.  If it doesn't crash within 3 times of doing 1500 runs, we say that the crash probably isn't going to happen in that version of the software.  So we've been selectively disabling parts of the software trying to figure out which code is triggering the crash.

Answer 1

Some more information:
In addition to not happening in LV2014x86, it does not happen in LV 2014 MacOS x64.  So this is specific to LV 2014 Windows x64.  Furthermore, if we save our code to previous and open it in LV2013x64 there's no crash (there's some hickups with the downgrade so it's not 100% apples-apples though) .
We have narrowed the crash down to a specific changelist in source code control.  In that changelist we changed the architecture of how we pass messages around in our program.  We used to use User Events to pass messages and the vi listening would subscribe to the user event.  However, we found this created a memory leak in LV2012.  So we switched to a queued based messaging architecture in this changelist.  We created a variant which held the queues as a variant attribute associated with the message enum.  This was so that when a message is sent we could do a fast lookup by taking the message and getting a varriant attribute associated with it (thus giving us the queues subscribing to that message).  When we introduced this in LV2012 we stressed tested it all and it worked great.  Later we upgraded to LV2014 and that's when the crashing started, we have gone back to this specific changelist and tried it with LV2014 it crashes.
We have found other parts of our code which if we disable the crashing goes away.  Our suspicion is that this occurs due to a perfect storm of calling vi's asyncronously (which call other vi's ascncronously), passing messages to them via queues, and maybe the variant's containing queues in attributes.  Based on what various programmers have seen via a variety of observations, our suspicions are that some combination of those circumstances is triggering some sort of LV2014 windows x64 bug.