I'm experiencing crashes with only Z3TA-2.1 and Sonar X2a.  I have 9 other VSTs all working with no issues.  Sonar itself is very stable with regards to both MIDI and audio. 
 
I've tried raising my sound card buffers to 1024.  I've tried disengaging both antivirus (Microsoft Security Essentials) and my wireless network.  They're not causing it.  I've got no other problems with this DAW.  Z3TA crashes about once every half hour or hour.   I have 16GB of memory, 2 fast hard drives, an i7 chip and everything is 64 bit, Windows 7.
 
Anyone experience this and did you get it resolved?  
 
Thanks,
Jerry
www.jerrygerber.com

I would uninstall Z3TA and reinstall it. 

You probably wouldn't uninstall and reinstall it if you already had done it three times.
I went into the registry and removed the correct keys, to make sure I really uninstalled it, as per instructions from Cakewalk. A clean install doesn't stop the crashing. 
 
It only crashes as a VST, not in standalone mode.  I made some changes to Windows, as many audio experts recommend: turning off disk indexing, having discs in DMA mode, having the page file's initial and maximum values the same (about 1/4 the amount of RAM in system).  Fairly clean install of Windows too, only a few months old.   None of the common Window tweaks fix the issue, as I said no other problems with 9 other VSTs...
 
 

send a project file, with just zeta in it, into tech support so they can take a look... it's their flagship synth and it crashes their flagship host, strange that it got past qa...

Can't say I've ever had Z3TA crash SONAR before...  so yeah, it would be best to send in a crash dump to CW for review. 
 

I think I resolved it.  There's a setting in Sonar's Aud.ini file called "ExtraPluginBufs".  This setting allows more memory to be given to plugins that need it.  The default is "0".  I changed it to 64 and haven't had a crash all day.  I'll be able to confirm after a day or two, but I am reasonably certain this did the trick. 
Since I was on the phone with tech support at least 3 times about this issue, I am surprised it wasn't mention in the troubleshooting.  It would have saved me a lot of time.
 
p.s. For those that don't know, and have this problem the aud.ini file can be edited by going to Edit-Preferences-Audio-Configuration File.
 
JG
www.jerrygerber.com