I am also having serious issues with VE Pro 6853 - and as you posted in this thread, Phil:
http://community.vsl.co.at/forums/p/26428/174136.aspx#174136
I suspect there is something going on between Kontakt 4.x and VEPro 6853
I had never used K4 until I installed Alicia's Keys (worthy of a thread of its own, this instrument is a joy), bundled with the K4 player. I took K4 player to the latest build, (4.1.1.3832, same as the version you are using).
I also installed VI Pro, but have not actively started using it. Still in test mode. So VI Pro is not in use in any template right now.
1. Make a new session in protools. 24-bit/44.1 - ProToolsHD 8.01cs22. Make a new instance of VE Pro 32-bit server on a slave machine (mac book pro, OS 10.6.4)
3. Delete all channels from the VEPro default, then add an instance of Kontakt 4. Load a good sized patch, such as Alicia's Keys.
4. Make a stereo aux in ProTools, instantiate VEPro plug (6853) and connect (1 buffer)
5. Make a stereo instrument track in ProTools, assign midi to VEPro server and route audio as needed.
6. UNPRESERVE the instance in VEPro server.
7. SAVE the protools session.
8. CRASH
Could it be related to the amount of data that VEPro is trying to save into protools? This only happens when saving (command-s or auto-save)
I could revert back to 6150 for today, and see if things change for better or worse. The other possibility is to keep using 6853 and eliminate Kontakt 4 from the workflow. Which I can do... but I've been really loving Alicia's Keys and I'd hate to lose it.
Another data point: since I have 2 slaves (macbook pro, OS 10.6.4 and WInXP, both 32-bit servers), don't know if Kontakt 4 can play nice with protools in 6853 if I eliminate the mac slave... this is going to take some time to fully troubleshoot. Hopefully VSL can test this for us?
The one thing that we both have in common: OS 10.5.8 on PPC with PTHD 8.0.1cs2 as host.
For simplicity, I am first going to eliminate Kontakt 4 from my workflow and see if this helps, since this is the only change to my rig besides 6853 and VI Pro (as I said is not in use). Then if I must use Alicia's Keys, I will load it on the XP machine (I tend to load certain instruments on the same slave for consistency, but I have it on both slaves). Then if that's happy, we'll know that K4 in VEPro on the mac slave is the issue.
My session is gonna go all day/night (I have a parade of soloists coming in today, all day), so I'll report back after my musicians leave.
J