This probably isnt that helpful, but i have been pro actively trying to narrow down why i get x2 crashes over the past couple of months..
I find that when using 64 bit plugins and synths only, sonar x2 is pretty stable. I dont run uad stuff which seems to be problematic. i think they now have 64 bit drivers released in december..
When using 32bit synths or plugins... and a good few of them, thats when i run into troubles. I am of course running 64bit sonar.
I have tested only using sonar 64 bit plugins and effects and it is rock solid.
The other thing i have noticed is that i have a lot of USB devices connected to the computers own usb ports which i found to be troublesome.
I had a minibrute/tetra/maschine/scralett 8i6 all in the motherboards usb ports, as well as mouse, qwerty keys, external hd.
I was advised to get a seperate usb card and run as many hardware synths (minibrute,maschine,xv5050 etc) into this seperate usb card, which runs on a seperate usb bus, leaving mouse, qwerty keyboard and drive using the motherboards usb ports.
It does work better and more stable since then. Getting rid of default omni midi settings also helps and setting up devices to respond to exclusive midi channles for them may well have helped as well.
non x2 Plugins that are rock solid for me in x2 are...
Massive/Maschine or any NI stuff/diva/all free 64 bit plugs on kvrs site/izotope5advanced/
Getting rid of default omni midi settings also helps and setting up devices to respond to exclusive midi channles for them helped a lot as well.
...As does having an autosave on every 20-30 changes. Thats a good feature instead of setting it to every 20 minutes or so.
Agree it can be extremely frustrating. Just my experiences trying to get a stable system, by no means gospel. You have probably tried all of that. Anyway..
Hope it gets sorted.