My system isn't tweaked.  The drivers work great in X2 and it was showing up in X3 at first, it even let me set up the control surface mode of the M-16dx on the midi side just like X2.  I'm going to uninstall it and try a fresh reinstall this weekend.  X2 (and X1) work flawlessly for me and I got some excellent results.  At some point soon my time will become worth a lot more than the cost of X3.  I've been using various Cakewalk software since '99 and this is the first real problem I've ever had with any of it.

If possible, give tech support a call before re-installing. There might be a simple fix.

Sorry to hear you've been having problems. If you get the chance, give us a ring. Tech support is free for SONAR X3 (other than the cost of a call). Our emails are a bit backed up right now from launch volume.
 
BTW, if you had a bad crash like that and your audio drivers disappear, try rebooting the system versus uninstalling/reinstalling. If you had to forcefully end SONAR from the Task Manager then the drivers for your audio device are probably still "in use" and weren't released properly. Easiest solution for dealing with that is usually a ol' fashion restart.
 
If you crash again like that and the Fault Reporter comes up, definitely send the report through. Tell it that you want to be notified of the status and it will assign a "CWBRN" number that we can more easily trace on our end.

townstra
I emailed them about a problem twice last week.  No response.  Now when I open X3 my audio interface doesn't even show up.  X2 still works perfectly.  X3 is not looking like it is worth my trouble.

I suspect you just have to call them. For some reason, I never got response (X2/Waves issue) to a Support request through email, either.

I was having some weird issues with X3b with crashing as well. It seemed to be plugin related so I went to preferences/vst settings/scan options and chose Manual Scan. I've never had the need to scan my plugs every time I start Sonar.
 
I then checked Rescan failed plugins and Rescan existing plugins and clicked Reset. It totally fixed my issues. I think the rescan was the big one. And now with manual scan X3 loads super fast and the projects are much quicker to load. Maybe this will help.
 

tweak:
a fine adjustment to a mechanism or system
to change (something) slightly in order to improve it
 
If it does behave correctly it was not tweaked, it was twerked.
 
There are many services and tasks that should be disabled, for most all computer use:
   Examples
      windows media sharing network
      auto updates:   for all programs, and utilities
      auto defrag
      machine evaluation and reporting
       user groove eval and reporting
 
And a bunch of other stuff, especially for dedicated (audio) computers.
 
 
 

A cool useful utility to take a look at what processes are currently running and to see how much CPU each process is taking is Process Explorer:  http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx
I know its been mentioned before on various threads but what the heck...just in case someone is looking for it.

I rebooted my system again and it seems to be working now.  I have the VST scan set to start up instead of background.  Hopefully it will continue to cooperate!

Now that everything has been working correctly for a while I have to say I am really liking X3b a lot.  The Quadcurve Equalizer makes it so easy to notch out correct frequencies in my mix that I am thinking that is the new feature I will get the most use out of (even though I am liking the Tape Emulator quite a bit too).  Now I'm back to being a completely satisfied Cakewalk customer like I have been most of the last 14 years.