Well, James - that's an interesting find.  I will give the same a shot and see if it works here.  I've been able to reproduce this issue very reliably on one particular project.
 
In your contact with this guy Ulf at Melodyne, have you gotten any indication of their awareness of the issue, how long it has been a problem, contact with Cakewalk about it, and plans to correct it?
 

Just emailed Celemony.  Got a generic computer response asking for serial number. Replied to that email with my Ser#.  Hope that helped that total emails about the problems.  If we could get more people to join in!!  I did notice accidently less crashes with melody edit window opened.

Starting with 2016.08 V-Vocal is also crashing Sonar when creating a region FX. I hope this is related, since they're not likely to spend as much time on something that affects V-Vocal.
 
IN my case it doesn't happen that often. Here's what fixes it for me. Freeze synths to free up memory, even if you're running 64 bit Plat like I am. Go to utilities and choose convert to 24 bit, if you're mixing formats. Erase the pic cache.
 
It'll be interesting to see if these fixes help with Melodyne

Is this still happening in the early access build for 2016.09? I replied to your case.
We will need more data if it is project specific. I was unable to reproduce it.

FYI: Doubt I'm the only one but Celemony is having me test a beta version of the bug release. I'll follow up later.

Noel Borthwick [Cakewalk]
Is this still happening in the early access build for 2016.09? I replied to your case.
We will need more data if it is project specific. I was unable to reproduce it.

 
Thanks Noel. I saw your bug report message and I responded to it and uploaded a bun to MS Onedrive for you. I just tried it in 2016.09 early access and it still happens with that version also. I appreciate your efforts on solving this.

May I ask: where exactly are we on the Melodyne 4 problem? (I still have Melodyne 2 on my computer,  have downloaded Melodyne 4, but hesitate to install it until I know the hassles are gone.)
 
I have installed Sonar Platinum 2016.09 Second Release, if this helps.

I just had the problem, but I have managed to get going again (this thread helped).
 
Manually update Melodyne. 
The crashing version was: Melodyne.4.0.4.001
In Melodyne if I clicked Help -> Check for Updates, it claimed to be the latest version.
 
The latest version on the website was: Melodyne.4.0.4.004.
 
Then I followed some of the other advice on the forum:
- uninstall old version (Melodyne.4.0.4.001)
- run CCleaner
- reboot PC
- install latest version (Melodyne.4.0.4.004)
- in Sonar create a new track, move one clip into the new track
 
Melodyne opened the clip. 
 
So far... so good.

Not fixed unfortunately - it just crashed with the latest version.
 
There does seem to be a workaround - move clips to a new audio track.
 
Faulting application name: SONARPLT.exe, version: 22.9.2.42, time stamp: 0x57f9caf1
Faulting module name: MelodyneCore-4.0.4.004.dll, version: 4.0.4.4, time stamp: 0x56f43463
Exception code: 0xc000041d
Fault offset: 0x0000000000de96b7
Faulting process ID: 0x2be4
Faulting application start time: 0x01d22e2d9ea0d802
Faulting application path: C:\Program Files\Cakewalk\SONAR Platinum\SONARPLT.exe
Faulting module path: C:\Program Files\Common Files\Celemony\Bundles\MelodyneCore-4.0.4.004.dll
Report ID: ff0a7ec5-e415-4bf8-907e-eac79dcc12b3
Faulting package full name:
Faulting package-relative application ID:

tonydude
Not fixed unfortunately - it just crashed with the latest version.
 
There does seem to be a workaround - move clips to a new audio track.
 
Faulting application name: SONARPLT.exe, version: 22.9.2.42, time stamp: 0x57f9caf1
Faulting module name: MelodyneCore-4.0.4.004.dll, version: 4.0.4.4, time stamp: 0x56f43463
Exception code: 0xc000041d
Fault offset: 0x0000000000de96b7
Faulting process ID: 0x2be4
Faulting application start time: 0x01d22e2d9ea0d802
Faulting application path: C:\Program Files\Cakewalk\SONAR Platinum\SONARPLT.exe
Faulting module path: C:\Program Files\Common Files\Celemony\Bundles\MelodyneCore-4.0.4.004.dll
Report ID: ff0a7ec5-e415-4bf8-907e-eac79dcc12b3
Faulting package full name:
Faulting package-relative application ID:

Thanks, Tony; I appreciate your response.
 
Maybe I'll just hang tight at Version 2 for a while....