Working with the latest version of Melodyne Assistant in the latest version of Sonar Professional.
 
Applying MDyne as a region FX on a small vocal clip. Literally four words. I can launch Melodyne as a Region FX. Do a simple pitch tweak. Close Melodyne. As soon as I try to Render Region. MDyne locks up Sonar, which quits responding. At that point I have to task manager/End Sonar. 
 
Any ideas?
Thank you!

I've only used the latest MD update (4.1.1) a few times, but so far it seems stable here. 
 
Does it happen on any/every clip or track?

Are there any FX on that Track you are using Melodyne on ?
Are the sample rates high ? normal bit rate ?
By " Render Region" you mean bounce to clips correct ?
It might not necessarily be a Melodyne issue but possibly a conversation issue when you are bouncing to clips.

stevec
I've only used the latest MD update (4.1.1) a few times, but so far it seems stable here. 
 
Does it happen on any/every clip or track?

I've only tried it on the one clip. But I see your point.

I never "close Melodyne" before rendering. Is this something that usually works for you? Do the pitch tweak then bounce it to clips is my methodology - never had any trouble. Melodyne closes itself during the bounce process.

chuckebaby
Are there any FX on that Track you are using Melodyne on ?
Yes. Maybe disable them first?
Are the sample rates high ? normal bit rate ?
All the normal default settings.
By " Render Region" you mean bounce to clips correct ?
No. I right click on the clip header to access MDyne Render Region FX. I believe it's essentially a bounce of sorts, but I don't go to the clips sub-menu and use the specific bounce to clip function.
It might not necessarily be a Melodyne issue but possibly a conversation issue when you are bouncing to clips.
Understood. I'm really pushing my CPU at this point in the project. May have to bounce some plugin-heavy tracks, eliminate the plugins to reduce the load. MDyne may be more than the CPU can handle.

I suppose you might be able to try a test project:
Load 1 audio track (No FX) in the project and try to use Melodyne on that audio track.
This will (at minimum) narrow down weather or not it is project related.