Did a search on this but found nothing.
 
OK. So I created a batch of 10 songs over the course of 2 months. Rubbing my hands together, anticipating the vocal tracks. Fire up Sonar, and whaddya know... it can't find any plugins. The dialog says they may be incorrectly installed. Nope. Re-scanned the plugins TWICE. Everything is where it should be.
 
Here's the kicker: It is only the Kontakt instruments that Sonar can't find/load. In the Browser, all of those synths are grayed out. If I delete those "gray" synths, I can open up Native Instruments, and re-add the instrument. Everyone say, "Kum-bay-YAY!"
 
Unfortunately, everything I've ever created (couple of hundred tunes) has this error. 
 
To answer some inevitable "DUH" questions:

1. All NI synths and drivers are up-to-date.
2. Cakewalk's Command Center shows everything is good to go.
3. My machine is right and tight. Maxxed out RAM, CPU, etc. 

Are the paths to the nki files and sample data within Kontakt itself correct?   What you're describing sounds similar to what I see when I forget to turn on my external samples drive (the plugins themselves are on c:\). 
 

It always used to be said on the NI Forum that all NI instruments have to be run standalone before they will run successfully as plug-ins. To kill two birds, what happens when you do run them stand alone?

ChristopherM
It always used to be said on the NI Forum that all NI instruments have to be run standalone before they will run successfully as plug-ins. To kill two birds, what happens when you do run them stand alone?

I've never run NI instruments standalone and haven't had any problems with plug-ins
 
Walt

The NI instruments run fine as standalone, although I never use them that way. And, I can simply add them back into the broken song and the problem is fixed.
 
NI is telling me to reinstall the whole Kompakt 9. Reminds me of the early days when one's computer started acting up, the only solution was to re-install Windows (and format the hard drive!).
 
@ChristopherM: The NI plugins and song data are on the same drive. Sonar is on C:/ drive. 

Just a thought, but is this a 32- versus 64-bit thing? I'm not sure, but I think that it is necessary for NI's 32- and 64-bit VSTs to be installed in separate folders. Assuming yours are, is Sonar set to scan the appropriate NI folder? The only time that I can recall seeing greyed-out entries in plug lists in Sonar is when the plug in question is the "wrong"-bit.
 
Another thought: bear in mind that most of the lengthy install of Kompact is the sample libraries. Presumably, you are not being asked to do that. Installing (or reinstalling) the synths themselves is really quite fast. You could run the installer selectively for, say, only one of the instruments that you are having probs with, just to see if that solves the problem. That shouldn't take very long at all. 

Right now, I can create a new song, using NI's instruments, and have no problems. It seems to be just those that were created within these past 2 months that are bad. I'll re-build them (all MIDI-powered anyway).
 
If I delete the xxx.cwp.assets file, SOMETIMES a song will load just fine. Then I'll re-save it. For some reason, no new assets file is created. So it's an inconsistent error (what we call a CND (cannot duplicate) in the military when troubleshooting jets).
 
I sampled (loaded) some of my archived stuff and do not get any errors. I should be grateful for that, anyway.

Perhaps a full Reset and Rescan of all of your plugins would correct this?  You can do that in the Cakewalk Plugin Manager.
 
Bob Bone
 

Been there; done that.

A reluctant upgrade to Windows 10 has solved the problem of Sonar crashing. Had to get a new audio interface (no Win10 drivers), but I'm happy.