Hi, folks.  
Been using CW since forever, but for the past few weeks, Sonar X3 does not close down properly.  When I close it, it closes then says that SonarPRD.exe is not responding.  The it offers the usal options to 1) Check for a solution and close the program, 2) Close the program, or 3) Wait for the Program to respond.  Then it generates this information:
Description:
A problem caused this program to stop interacting with Windows.
Problem signature:
Problem Event Name: AppHangB1
Application Name: SONARPDR.exe
Application Version: 20.0.5.352
Application Timestamp: 5320c501
Hang Signature: d8bf
Hang Type: 0
OS Version: 6.1.7601.2.1.0.256.48
Locale ID: 1033
Additional Hang Signature 1: d8bff7159c77c0884acc72f3682aa0f8
Additional Hang Signature 2: f71c
Additional Hang Signature 3: f71c961e84fd34a4191a88587c91762c
Additional Hang Signature 4: d8bf
Additional Hang Signature 5: d8bff7159c77c0884acc72f3682aa0f8
Additional Hang Signature 6: f71c
Additional Hang Signature 7: f71c961e84fd34a4191a88587c91762c
 
It also does not save the last project in the drop down menu list of recent projects.  Any ideas?  Otherwise, it seems to work OK.  I just have to make sure that I save the file and then be able to locate it to open it back up.

P.S. I'm using the Producer edition and 64-bit version.

Sonar has at times been stopped from properly closing by a connected MIDI device that doesn't let go when Sonar closes. Easiest way is to check the Task Manager to see if Sonar is still running and look for some device esp a midi device which as I said can often be a culprit.

Audio interface drivers, if it's external then you can power cycle it, allowing sonar to close
Hth

OS?
My old win 7 system had this and was fixed when I went to Win 8 (and 8.1).
 
Mine was on a Delta 1010 card on Win 7 Ultimate 64 bit....having said that I was so annoyed by the lack of driver updates for the Delta 1010 I bought a MOTU Audio express and Win 8 at the same time, this resolved for me.
 
Now my Delta 1010 is my windows sound and my Motu a dedicated Sonar/Pro Tools card.

Well, guys, I'll definitely check out these suggestions.  I don't have a midi device plugged in at present, just speaker connections and the like on my Focusrite Scarlett 18i6.  I'm also running Windows 7 Professional 64-bit.  Mudgel, I will check Task Manager when I do this. Will also try lawp's suggestion about power cycling.  Markyzno, I'm really scared about going to Win 8.  I have it on two other computers, but I'm not particularly fond it...

If there are any loaded 32-bit plugins, sometimes BitBridge can hang things up.
 
You would see it in Task Manager.  Some folks do seem to get it sorted out by cycling the audio interface, as noted above.
 
Also, with regard to Win 7 and/or Win 8 and 8.1 - the biggest thing to make sure of is that our audio interface drivers will work properly in the OS version you load, (whether that is 7, 8, or 8.1).
 
I ran on Windows 8 for quite a while, then just last night finally got around to upgrading to 8.1.1 - whatever the latest version is.  I did that only after making sure my interface drivers would work OK, and they work just fine.
 
So, just do your homework on that.
 
Windows 8 actually works very well, but lots of folks completely lose it, with regard to the tiles and the start button and all that, but it is no biggie, and you will get the hang of it in no time, plus you can get a lot of the familiar look and feel back quite simply.
 
Bob Bone
 

FWIW, I also have a Scarlett 18i6, running on Windows 7 Home 64-bit.  Can't say I've run into this issue though.
 
Are you running X3e?   Does the same thing happen with a new, blank project?
 

Funny this topic, as I very very rarely have these sort of issues, But I just had this exact same thing happen to me early this morning. And oddly enough the same thing with the last project was not in the drop down menu??? I found that very odd. When I opened it by browsing it was fine. The thing is I had saved it a half dozen times as I worked on it, then I exported a mix and tried to close Sonar. Sometimes at this point some projects ask you to save even though you did before export. Is this related? 
 
But the comment about the midi device is what I think happened as my stupid Yamaha drums fell asleep and disconnected. Sonar told me. So that might have been it.. The other problem was my mouse battery died and it was behaving crazy as it breathed it's last breath, so I thought?? oh well. But that is odd we both got the identical weirdness.
 

I've had this happen a few times since the last Windows update, never before. Who knows?