Sonar is suddenly crashing (The "Sonar has stopped working" error) over the past 24 hours. I installed the latest updates 3 days ago.
 
It's only crashing when I'm working on Pro Channel plugins, although the plugin can vary.
 
Is there a troubleshooting document anyone knows of I can follow to find the reason?

A sudden and persistent bork out like this would have me concerned. More details (and smarter people than I) probably required but first you should back up any important projects ASAP in case this is hardware failure.
 
Then I guess I'd ask... have you changed anything else on the system recently like hardware/new programs?
 
It should be noted there was apparently some Adobe Flash player hack recently that has prompted security/update freakouts. Probably not the issue but if it's an online system maybe something nefarious snuck in.

Could it as easy as doing a vst reset, and a rescan? As mentioned, did you do any changes since the last time things worked as they should? Do you have the latest drivers for your audio interface? Windows up to date?
Best of luck.

Windows event viewer.

No recent changes. I've reset the VST's and will check the event viewer, then report back.

Try this.
 
Make sure Sonar isn't running
 
Navigate to %appdata%\Roaming\Cakewalk\SONAR Platinum
Rename the file AUD.INI to AUD.OLD
 
Now restart Sonar