I purchased X2 (and installed the X2a patch) two days ago and was enjoying it but using the quantize function on midi resulted in a bad crash. I had to reboot my computer about four times to allow X2 to load the project without removing all the audio devices. Finally, it loaded the audio devices and I can see them in the preferences but I no longer have any audio output. X1 does work so I'm not in a dire situation, but am slightly surprised by such a destructive crash a day or two into normal use of the program. Any ideas how to get audio play back to resume in X2a? I don't know what to do other than go through the very long uninstall/reinstall process and hopefully there is an alternative fix?? Thanks.

In preferences what audio device and driver is being used?

Sometimes when Sonar crashes, you'll need to power your AI down then restart your puter. You may not need to restart the puter but almost always, you'll have to restart your AI.

AI (audio interface)

I do not quantize in Sonar- it is not working any way the way it should. Make sure no audio deviced used by other application when you start.

Listing some of your specs might help get to root of problem.
 
It may seem a silly question, but did you check that your Master Bus fader was not set to zero?
 
Quantizing MIDI here works okay, so there must be a solution for you.

I have windows 7 64 bit, 24 gigs of RAM, and Edirol UA-101 interface. In the preferences, it shows input devices and output devices correctly listed. They are UA-101 In 1-10 and all have a checkbox. Master bus is not set to zero. This same project plays back properly in X1. No audio is working in X2a after it had a hard crash. Any ideas?

EDIT - Ok, I found a solution. In the Sonar x2 producer folder, I removed the AUD file (backed it up first). When restarting Sonar x2, it recreated the AUD file and audio is now working! :-D so it must have gotten corrupt when Sonar X2 crashed. Thanks.