Random data point. I'm running Melodyne Assistant 4.0.4.004 64-bit. I only ever use it as a Region FX from within Sonar Platinum -- never as an FX or the standalone. I do not have the 'automap' DLL, whatever *that's* all about.
 
I can keep multiple regions 'live' simultaneously as long as their on separate tracks. Useful for working on my crappy attempts at harmony. I then have to render them all out. If I forget, and try to create a second Melodyne Region FX further on in a track that already has one, bam! instant crash, every time.
 
There also seems to be an upper limit on the length of a clip that is being turned into a Region FX, though I haven't worked out exactly where it is. If I try to do an entire vocal track (say 3 minutes) it crashes *sometimes*. Keeping the clips shorter (30 seconds or so) seems to reliably work, however.
 
Thankfully, and for what it's worth, there doesn't appear to be any length issues when using the "compute a tempo map from this audio file" that's in Assistant and higher editions. I've fed it 6 minute long mp3s and it hasn't chocked on any of them.
 
It would be super keen to get this actually fixed, though. It's not acceptable that there's this ticking time bomb waiting to go off if I foolishly try to have 2 Region FX clips on the same track. If I want all my vocal tracks to be 'live' regions, it should let me. If performance degrades, fine, I'll lower my expectations accordingly -- but an instant crash and core dump is inexcusable.
 
FWIW, if this were properly fixed (after 4 months), I'd be somewhat more inclined to the 'lifetime' upgrades deal. 

I did the update to 4.0.4 before I found this forum.
 
After the update I got crashes and the preview of a note quit working. 
 
I downgraded back to 2.0, and I don't get the crashes, but now note preview does not work.

Bluegrasser 
I downgraded back to 2.0, and I don't get the crashes, but now note preview does not work.

Try enabling input echo if you haven't already.

Bluegrasser
I did the update to 4.0.4 before I found this forum.
 
After the update I got crashes and the preview of a note quit working. 
 
I downgraded back to 2.0, and I don't get the crashes, but now note preview does not work.

I didn't think you could roll back Melodyne.  How did you do it?

I did some troubleshooting this evening.  I have 132 projects with 75% of them containing Melodyne 2.0 FX Regions.
 
I uninstalled Melodyne 4.0 using Control Panel->Programs and Features.
I uninstalled SPLAT and reinstalled both.
 
 
I created a new Project and tested Melodyne 4.0 on a new clip.  Works ok.
 
 
When I open a project with a Melodyne 2.0 Region I get the warning that there is no going back.  Sonar crashes.
I can reopen the project after the crash and audition does not work.  In the Melodyne 4.0 window in SPLAT I can see audio being sounded in the box beside the "Compare" Button.
 
 
I tried Input Echo on and it made no difference.
 
 
I have backups of the Melodyne 2 projects I opened in Melodyne 4, so I am going back to Melodyne 2 until this stuff gets worked out.

 
Bad news from testing this morning.  Audition of a blob does not work at all in any of my existing projects using Melodyne 2.  It works ok on a new project.  I have tried reinstalling SPLAT and Melodyne 2 several times in different order with like results on existing projects.  The Melodyne window in Sonar shows activity in the upper left corner when I audition a blob, but no sound is coming through.  The Uninstalls I did were using Command Center, Programs and features, and for Melodyne the install package.


I think upgrading to Melodyne 4 and going back to 2 has messed up my DAW for using Melodyne except for new audio. 
 
I have Sonar installed on my Laptop, so the next step is to try an old project there.
 
I might try uninstalling Sonar and Melodyne on my DAW and then checking for ghost registry entries that the uninstallers may have missed???

The only clean way I found to back out of Melodyne 4 is a System Restore (simplest as M4 disappears and M2 reappears).

There are files in an M4 directory that created issues and were resolved by deleting that folder and reinstalling M4, but I forget the details of what I had done there. These "extra files" wrought havok on SONAR due to conflicting registry entries. Ultimately I passed on M4, so cannot provide much insight beyond the above.

Platinum been crashing since update. Most of the time with using melodyne..installed new version and now getting this crash error. If i go up to the menu and nudge something left or right I lose sound and it takes forever to get back on. any ideas?

The "Rdas" refers to the Roland VS drivers.    Unfortunately I can't offer much more than since I don't have a Roland interface, but I've seen the DLLs in a few other threads.  
 

Im using the vs 700R as the interface. Has worked great until last platinum update.