When i try to open the most recent projects in the folder, I get the following fatal error notice:
It is odd that some of the saved versions of the project in the folder load normally, even though they also have Melodyne sections in them (if that is indeed the problem)
Any suggestions would be appreciated!
Thanks
 
Windows 10 64 bitIntel(R) Core(TM) i7-4770CPU @ 3.40 GHz12.0 GB Ram64-bit operating system, x64-based processorFocusrite Scarlett 18i8

Did it save a recovery copy? 
Melodyn has caused me issues in the past so I stopped using it for vocals. I only use it to convert audio to midi and even then, the only projects that ever crash on me all had Melodyn involved. I posted this a long time ago asking if anyone else had noticed Melodyn causing crashes and nobody said a word. 

Thanks for the reply.
The recovery copy also crashes Sonar.

New development: Cactus Music's post made me dig further into past posts- and came up with this regarding Melodyne crashes:
Before all that; see if you can load the project in safe mode via holding the [Shift] key on open.

Best Regards,
Seth Kellogg
Opening in safe mode allows you to choose to load or not load plugins- I did not load any melodyne, and recovered the project (except for the Melodyne sections, which thankfully are smallish).

Thanks 

I've had the odd problems with Melodyne (and also previously with V-Vocal) when saving with the region fx active.
 
What I do now is bounce the clips after editing and remove the region fx altogether before saving. I can always create another to edit it if I need to, but once it's edited there's really no reason (for me anyway) to keep the region fx active.
 
M.