Hey Spacey, I too am sorry you're having issues. I know this is the last thing you probably want to do...but have you tried a complete uninstall using the method Cake recommends and also removing the important registry items?
I say that because my initial install of X2 on my good machine sort of forced me to do that. I removed all versions of Sonar except for my good version of 8.5.3. I had Sonar 6 all the way up to x2 on there. LOL! So that was an accident waiting to happen for me. But once I removed all the older versions and then did the reinstall, X2 was great for me. Also, because the X2a patch was out, I didn't bother with the quick fix. I installed X2, and then patched it with X2a before I even opened it for the first time.
Next, some people will fight me to the death on this...but I sincerely feel 64 bit Sonar has issues. I don't know what the heck it is, but I can't get through a single session without a crash. Now with the 32 bit version, which is the one I've been bragging about as being near perfect for me....it really has been quite good. But 64 bit....something ain't right there.
If you're using 64, try uninstalling it and running the 32 bit version. We have enough horsepower with our systems these days to where that 64 bit stuff isn't as important as people lead us to believe.
I use loads of plugs and VSTi's in Sonar 32 bit and NEVER have to freeze any tracks. I mean seriously...how often will you use 15 synths to where 64 bit would actually help? Most of my projects for myself and clients end up being anywhere from 40 tracks to 80 +. This usually is more audio than synth oriented...but at all times, I usually have 3 drum modules, something from East/West, Dim pro, Kontakt etc and my cpu never goes over the halfway mark.
Running the same project in 64 of course uses less cpu, but then the crashing starts. I really think something is weird with 64....if you can muster up the desire to try it, try 32 for me and see if it makes a difference stability wise. I don't know if its due to 3rd party plugs in 64, or something wrong with the program, but man....it just never works right for me. It's like 32 bit Sonar and 64 bit Sonar are two different animals for me.
If all else fails brother...as much as it may be against what you believe in, 8.5 is a solid DAW. Nothing wrong with reverting back so you can get some fun out of the program. I use 8.5 as my weapon of choice to this day. To be honest, if all my buying power and technology advancement was taken away from me, I'd be perfectly happy with 8.5 and the stuff it has for the rest of my life...truth be told.
-Danny