In this particular project only two 32 bit plugins: Sonitus delay and Poulin LeCab,  both on muted audio track (never had a problem with them before in a lot more plugin intensive projects). Is the "sonar ending with buzz" scenario familiar ? 
 
I just have left the project running in a loop, crashed/hang again after 25 minutes with one Sample Tank3 instance frozen. It crashed/hang after 4 minutes with the very same ST3 unfrozen. It seems like ST3 has something to do with but then why crash/hang when ST3 is frozen?

Just a drive-by comment for the OP - you might consider replacing LeCab with NadIR (http://www.igniteamps.com/en/audio-plug-ins). It's another free plugin, but I've found it to be less crashy than LeCab, and it's available in both 32 bit and 64 bit form to remove any Bitbridge-related risks.

Kylotan
Just a drive-by comment for the OP - you might consider replacing LeCab with NadIR (http://www.igniteamps.com/en/audio-plug-ins). It's another free plugin, but I've found it to be less crashy than LeCab, and it's available in both 32 bit and 64 bit form to remove any Bitbridge-related risks.

Thanks! I will give it a try.

Kylotan
Just a drive-by comment for the OP - you might consider replacing LeCab with NadIR (http://www.igniteamps.com/en/audio-plug-ins). It's another free plugin, but I've found it to be less crashy than LeCab, and it's available in both 32 bit and 64 bit form to remove any Bitbridge-related risks.

+1 on NadIR

I'm having the same issue. Any time a VST2 plugin is inserted, SONAR Platinum with the Newburyport update crashes. I actually did a reinstall following instructions I'd received last year from support regarding a different issue. Will be submitting another support ticket. This kind of crash did not occur with any previous update.

Afrodrum
In this particular project only two 32 bit plugins: Sonitus delay and Poulin LeCab,  both on muted audio track (never had a problem with them before in a lot more plugin intensive projects). Is the "sonar ending with buzz" scenario familiar ? 
 
I just have left the project running in a loop, crashed/hang again after 25 minutes with one Sample Tank3 instance frozen. It crashed/hang after 4 minutes with the very same ST3 unfrozen. It seems like ST3 has something to do with but then why crash/hang when ST3 is frozen?

I'm not sure why you are using the 32 bit version of a Sonitus plugin.  They come with 64 bit versions.