Ah Ha!  No plugs, no problem.  Turning them on one at a time now I guess.

FWIW I've been told that the vast majority of tech support calls involve issues with third-party plug-ins. 

All the plugs I have were supplied with the various upgrades to Sonar.

Possibly a 32-bit plug-in living in a 64-bit world?

Could you please list all of the plugins that this project happens to have in it?
 
And, are all of your plugins current versions from the vendors?
 
Lastly, is your Windows up to date with maintenance?
 
It is good news that it is a single project exhibiting these problems, as that usually means one or more of the loaded plugins are having a bad hair day - possibly even with certain presets.  the problems vanishing when they are not loaded is a good indicator that this is a likely source of the issues.
 
And REALLY lastly, are the drivers and/or firmware for your audio interface current?  
 
Bob Bone
 

Check:
http://www.cakewalk.com/Support/Knowledge-Base/2007013315/SONAR-X3-Full-VST-Rescan-Recommended-for-Upgraders
 
Thanks.

Plugs in use:  Breverb 2.0.10 / sonitus reverb, fx gate and equalizer, MAudio driver bit depth 24, ASIO reported latencies input 3.6 output 3.3 roundtrip 6.8, sample rate 48000, buffer size 128, Maudio driver recently updated version 6.0.8 
 
I deleted all the plugs, second save crashed, deleted all synths, second save crashed, deleted all audio tracks, no problem!  Now I have 20 midi tracks with events in place and am in the process of rebuilding the audio tracks one at a time, will let you know when or if crash happens. 
 
By the way, Addictive Drums is very interesting, going to incorporate that one for sure, need to read the manual.
 
Thanks, Ron

Try saving as a bundle.

OK, thanks

Saved old file with audio tracks, plugs and synths in place as bundle, closed, opened back up, crashed on third save.