Keep in mind I'm using a i7 Quadcore and 64 bit Windows 7  X2 Producer 64 bit.....   This link here really helped: http://www.cakewalk.com/Documentation/default.aspx?Doc=SONAR%20X2&Lang=EN&Req=INI_Files.6.html
 ,,,, The three changes that seemed  to be important were changing the plugin buffs setting to (128 ) and thread scheduling model to ( 2 ) this is for folks with quad processor  and drop out ms to 500. now go through and read the description on all of them ,,,, Those three seemed to be important to my system,,,,,,     Before I found this info ,, I was only having problems as the project got bigger and bigger( more plugins more tracks more overall CPU load).  then More problems would start popping up ..... since these changes I worked all day yesterday with not one crash and I could even open V-Vocal with success on that same big project ..... Try it and see if it works for you .

So, this post has made my life better. Thank you!

None of these settings work for me. I can't use V-Vocal on any project. there has to be more info about this on here. I searched but found nothing. I'm sure others are having this problem. I should have stuck with X1, I had no problems with it. I think I'm done with upgrades.

Go figure, My X1 crashes now when creating a v-vocal. I guess X2 and X1 share files and now my X1 is screwed. Thanks Cakewalk.

You are suggesting that x1 and x2 share the ini file? Did you back yours up before altering it? If you are on Windows 7 or 8, you might be able to right click the file and restore to a previous version.

I use Sonar Producer X2 and X1 x64 and they do not share aud.ini files. The two files are found at this path
C:\Users\Geoff\AppData\Roaming\Cakewalk
and in a folder for x1 and x2 respectively.

> I guess X2 and X1 share files and now my X1 is screwed. Thanks Cakewalk.

Er.... nope. Guess again...

You can always reset your AUD document to default  I just cleaned out my old versions of 8 ,,,8.5,,,, X1  and deleted all those folders related to them ........ I  might just go knock em out of the registry .... But for the first time in 5 months I'm not getting any Crashes .... So I'm Gonna leave it alone

@bobgassert Oh but why leave it a lone? trouble shooting computers is what we live for, right?

@Mosvalve.  V-V failed entirely for me running 8.5.3 and I'd given up.  When upgrading to X2 I decided to just blow everything away and start from scratch, and for now at least V-V is working.  There's been plenty of threads about this, ultimately I think V-V is extremely sensitive to the setup/plug-in/hardware profiles - some have no problem, others a nightmare.  It probably needs a wholesale rethink.

@Mosvalve, you are correct in that X2 does overwrite the contents of the "Shared" directories and Vstplugins. Those directories are used by all versions of SONAR. One of those directories "Shared DXi" contains V-Vocal. It would appear however that V-Vocal was unchanged from X1 to X2.