Export Problem

I'm having an ongoing problem when I attempt to export audio from Sonar into wav format. The early parts of the project export properly, but as I play through the exported file, more and more of the individual project tracks have dropped out. IOW they were not exported from Sonar into wav format. So for example, my current project has about 25 tracks, including bass, various keys and guitars, drums, several vocal tracks, etc. After exporting the file I imported it into Sonar to check it, and I can see by the waveform that it is becoming more sparse as the file nears its end. So about half way through my latest export attempt the keys drop out, then the vocals, then everything but the drums, then the drums. BTW I get different results with each export attempt. Also, the original multi-track project plays through perfectly. And I've had this problem with other projects.
 
This problem makes Sonar, an otherwise fine program, pretty much useless to me. Any help would be greatly appreciated. Thanks.

All tracks are (or at least WERE audio...read further.) I had one composite MIDI track for drums, which I froze.
 
Disabling Fast Bounce made no difference.
 
Just for ha-has I unfroze the drums, at which point the following message box popped up:
 
"Addictive Drums 2

 
Wrong binary location
 
You are running a binary that is not the same as the one updated by the XLN Online Installer.
Please check your path settings by clicking the Advanced button in the XLN Online Installer and make sure that it matches with the plugin path setup in your host."
 
Which I think is a fancy way of telling me the AD2 plugin is not where XLN thinks it should be. So I moved it to the proper folder and re-scanned my plugins, and now I no longer get that message. However, now there's some other AD2 error message (for which I will probably have to contact XLN, because I have no idea what it means), and when I freeze the drums it produces no drum audio on the audio track associated with the drum MIDI data.
 
I have no idea as to whether or not this problem is related to the export problem.
 
 

In this project I have several folders so I can keep things organized...a folder for vocals, a folder for rhythm guitar parts, etc.
 
On a hunch I removed all the final tracks from their separate folders, and moved them into a new folder, so they'd all be together in one folder.
 
I then exported and it worked perfectly. I tried it more than once, to make sure.
 
Why should this be a factor, and has anyone else experienced this?