Sonar crashes when saving project

Make sure all your VST's are 64bit compatible
How are you saving? can you describe the steps and the settings you save in
Cj

Are you by chance using Vienna Ensemble Pro? I had an issue like that when Sonar was trying to communicate with my slave computers and it would just hang. This was an issue with Vienna Ensemble though and they have workarounds for it.
Also sometimes having too many VSTs will sometimes cause this issue. Do you use PLAY? I started getting these issues once I was using Play and Vienna. Kontakt always worked fine. Worst case maybe deactivate some VSTs before saving. This issue almost cased me a heart attack on my last project when I tried to save something and lost alot of work. Still having nightmares about it actually

  I believe these problems always occur when you fall too far behind in updating and upgrading computer technology. I'm thinking any number of the 1000's of security patch updates Win 7 has received over the past decade could wreak havoc on Sonar 8.5.
 Why are you still running a 32 bit version of Sonar on Windows 7 x64?
 I still have a 20 year (?) old, old, OLD Rain laptop that refuses to die that's loaded with XP and Sonar 8.5 Producer and it still rocks as a solid performing, but extremely limited, almost wimpy DAW compared to Sonar Platinum. A lot of cool, useful, and exciting things have happened to Cakewalk DAW technology since..
 
 Why are you still using the ancient v8.5, which I believe was optimized for Win XP, when you an get a modern day, infinitely more refined, STABLE and powerful version of Cakewalk by Bandlab?
 It will cost you NOTHING to upgrade to CbB except for a bit of a learning curve getting used to a newer sleeker Skylight interface.
 
 Or....
 The only sure way I know how to keep rock'in on and productive with Sonar 8.5 is to install it on a Windows XP SP 3 machine.
 

If this started recently, I would certainly check the latest vst you added or any pertinent audio program.