I'm using windows 7, I had Sonar 8 installed and it's updates. Last week I installed Sonar X3 producer. I had this problem that I could open a virtual synth, and if the track had midi data in it, the soft would play it, but then if I play the keyboard nothing happened, no sound would come out. So I played around a little with the configurations and stuff, changed the asio and wdm and all that. But the other day I double clicked on the icon and it never started. It looks like it's gonna open but it never happens. Then I open the task manager, and it is right there. So I end the process and I repeat the procedure, and nothing changes. I tried installing the update, same problem. I uninstalled and reinstalled everything, same problem. 
Any ideas would be immensely appreciated!
 
Marcelo

There are some times when this will happen. You need to kill it in Task Manager to get it to start next time. To remedy this, is to uninstall, reboot, and re-install. I'm not sure what the cause is. Has anyone in Windows7-32-bit or Windows 8 experienced this?

In the past it was due to a MIDI or audio device driver not letting go of the connection. Sonar wont shut down because its waiting for the driver release. 

Thanx 4 the replies!
Brian: My problem is that I kill SONARPDR.EXE in the task manager and when I try again, the problem persists. It never starts. I've already uninstalled and reinstalled the software...
 
This is very strange, because it doesn't happen with Sonar 8. Does this mean I will never be able to use SONAR X3? 

Have you done a cold reboot yet?

Hey musicroom! I just did that and it worked! Rebooted in safe mode. 
Why did this happen?
Thank you sooooo much!!!

This happens to me on certain crashes. Ever since I got the Octa-Capture it happens more often.
 
Powering down the audio interface usually frees the process so it can be killed. So that would be:

• power down audio interface
• kill sonarpdr in task manager
• power up audio interface
• try opening SONAR again

Most times this works. Sometimes SONAR will refuse to see the audio interface on reboot, in which case a system restart is needed. 

Sometimes drivers/programs hang and a cold reboot will reset the system.

if on windows 7 just "log out / sign in.
its faster than a cold restart.