I'm unable to mixdown a song (23 tracks). Had no problems before with it. It gets to the same point and stops, showing the error dialog. The song is also one of those that plays up to a certain bar and quits.
 
The only workaround is to mix the vocal tracks down separately from the instruments and then combine them together. Any ideas?

I've got the same thing happening on a couple projects. I've done a couple workarounds.
One was to take the tracks that were causing the error out of the track folder. Not sure why this makes a difference but it did. The other was to delete to corrupted clip and re-record it. The project usually stops playing just before the corrupted clip. Very frustrating. Never had this happen before and I've been using Cakewalk since 1999.

Possibly you have a plugin issue . . . have you tried loading the project in safe mode (hold down shift key while opening the project) then play the project with no plugins. If it plays well, try to open again and discover and eliminate to see which plugin may be causing the issue.
 
What does the "error dialog" say ?
 
Are you able to freeze any tracks, and then have the export render (mixdown) work properly ?
 
Can you give more information about the nature of your project, and what add-ons or plugins you may be using ?
Also, you signature doesn't say which Sonar version you are using.

No external plugins. I tracked down the corrupted clips (a short vocal that repeats during the chorus). When I remove the Breverb plugin from the track, the problem goes away. Here's the dialog:

It seems from a quick check of that error in combination with Breverb, that there may be some memory constraint issues that are contributing to this error.
 
What is your project Sample Rate?
 
What exact plugins are loaded into this project?
 
What other information can you tell me about what you are doing with this project, the steps you are following, etc...
 
Bob Bone
 

Some suggestions:
 

• If you're not using fast bounce, try it unless you're using MIDI FX. Real time bounce will be constrained by resources.
• Increase the latency. It could be that at some point, the system goes over the edge for resources and there's a dropout.
• Save the Breverb preset. Copy the track with it. Render the track with Breverb. Remove Breverb from the original track and archive the track.

Thanks, Anderton. What's "fast bounce"?
 
I don't like how Sonar copies tracks (bouncing), causing the hard drive to become pregnant with a lot of files. In Vegas, you can copy a track or clip any number of times and it just "points" to the single file. But I love Sonar too much to ever consider changing my DAW.
 
I just read where X4 is coming soon. It'll be interesting to see the improvements.

Ricebug
Thanks, Anderton. What's "fast bounce"?

 
I thought by "mixdown" you meant exporting or bouncing to a track. Fast bounce doesn't relate to real-time playing, so ignore the bounce comment but do try the other two suggestions.
 
FYI if you select all the tracks and choose "Bounce to Track(s)," you can mix them down to another track. When you do that, you have the option to "fast bounce" the tracks. This is what I do with mixes so the mixed files are contained with the project.
 

I don't like how Sonar copies tracks (bouncing), causing the hard drive to become pregnant with a lot of files. In Vegas, you can copy a track or clip any number of times and it just "points" to the single file. But I love Sonar too much to ever consider changing my DAW.

 
Actually, both programs work very similarly. In SONAR if you copy a track by, for example, dragging a clip to another track, then SONAR just points to the existing file. Try it - open the Media Browser to the Project Audio Folder, and you can copy all day without seeing any files added. However, bouncing is a destructive edit, so SONAR has to create a new file and keep the old one for undo. Vegas doesn't really do bouncing (I wish it did; sometimes it would be nice to consolidate video or audio clips into a single file, although my workaround is grouping). The way you bounce in Vegas is to render the file, then bring it back into the project, which ends up creating another file.
 
Please report back if the other two suggestions made any difference, I'm curious now 
 

I get this, usually on massive feature film projects.
 
So, i'll play the project from the start and wait for an audio dropout, then at that point I join the clips together on their separate tracks, this resolves the issue for me.