If I am working on one song, close it, then open another quickly, Sonar will chug and chug and go into "Not Responding" state.  If I close out of it, the only way to re-open it is to completely shut down the computer/restart.  This is really aggravating.  X2 has been pretty buggy for me so I was hoping the X2A update would fix everything.  It fixed some things, but now I've run into this issue.
 
Running Win7 Home Premium 64-bit Service Pack 1
HP Pavillon H8-1214
AMD FX-6100 Six-Core Processor @ 3.30 GHz
10.0 GB RAM
M-Audio Mobile-Pre Interface
 
Thanks.

Try it with two brand new X2A projects and if you are running realtime antivirus scan MS recommends excluding:
 
 
C:\windows\SoftwareDistribution\Datastore\Logs\res*.log
C:\windows\SoftwareDistribution\Datastore\Logs\res*.jrs
C:\windows\SoftwareDistribution\Datastore\Logs\edb.chk
C:\windows\SoftwareDistribution\Datastore\Logs\Tmp.edb
c:\windows\Security\Database\*.edb
c:\windows\Security\Database\*.sdb
c:\windows\Security\Database\*.log
c:\windows\Security\Database\*.chk
c:\windows\Security\Database\*.jrs
C:\ProgramData\NTUser.pol
C:\Windows\System32\GroupPolicy\Registry.pol
 
I also exclude the Cakewalk Content and Project folders.
For bug fixes you really need to come to the X3 side I'm afraid, but I'm doubting your issue is exclusively a Sonar issue.
 

This has really become an issue.  I didn't have this issue with X1.  It started with X2.  I bought X3 hoping that would fix it, but it has not.  I reloaded X3 with all my antivirus turned off and it still does it.  It will just sit there with the little circle going round and round and round and will never load the session.  I never thought I'd say this, but I'm about to go back to ProTools 8.  I can't be in the middle of working with a recording then have to reboot my entire computer in order to launch X3 then have to reboot it again in 5 minutes.  It's unbearable. 

After upgrading to X3 was the plug-in inventory rebuilt, (see http://www.cakewalk.com/Support/kb/reader.aspx/2007013315)? Probably not the problem as the issue is a carry over from X2, although a reset may have fixed it in X2. Also make sure to apply the X3d patch.
 
Try opening the projects in safe mode by holding the SHIFT key while opening the project. There may be a problem with one of the plug-ins.
 
Using any 32bit plug-ins?
 
Are there any older (XP era) plug-ins in use, if so, try running SONAR as administrator.

The use of 32-bit plugins in 64-bit Sonar will often leave BitBridge or JBridge running in the background for a bit, and this will cause Sonar to become unresponsive, at times, until the bridging software is released from memory.
 
I have seen this sort of thing reported more in the past, as more folks are using 64-bit plugins these days, but it does still pop up from time to time.
 
Bob Bone
 

If it only does it when you open a new project quickly, as you say, wouldn't the easiest workaround be allowing SONAR to close/save the previous project properly before opening a new one?
 
I've experienced similar symptoms with many softwares, PCs and combinations. I don't know what exactly was the cause at any particular time, but I can imagine there can be a million reasons for such, and I bet you can't be 100% sure it doesn't pop up with any other software or setup. So if waiting ten seconds helps, why not wait?
 
The suggestions above do sound logical to me, too.

Actually it doesn't always happen when I try to open things quickly - although it happens more often that way.  It also happens when I try to open certain older sessions created in X1 Studio or X2 Producer.
 
I do have 32 bit plugins I'm sure, but I couldn't tell you all of them offhand.  I use Toontrack EZ Drummer, Superior Drummer 2 and EZ Mix 2 all in 64 bit versions.  I have Melodyne Editor 1 which I THINK is 64 bit, but I'd have to check...that might be a holdover from my old XP computer.  I have several guitar amp simulators but I think those are all 64 bit as well.  I do have SampleTank 2.5XL and SonikSynth...I'm sure those are 32 bit...they're pretty old.  I also use IK Multimedia Battery - I should say I don't use it but have it on there and that's a 32 bit plug in.
 
I did load X3d...didn't help.  
 
Can I disable a plugin by removing it from the scanned library or is there a simpler way I can have it not grab a 32 bit plugin without moving it just so I can see if that solves the problem or not?
 
Thanks for your great responses.

Also....if I wasn't clear...the title of my post is regarding X2a, but I've since upgraded to X3 and have X3d update loaded.  That seems to have been a waste of money as I didn't need the upgrades X3 provided....I only upgraded to try to fix this problem.
 

Was X2 the first version of SONAR installed on this machine?
Is this the first 64bit version of SONAR being used?
 
As mentioned above, safe mode provides an option to load projects without plug-ins so it may help with diagnosing the problem.
 
VST plug-ins are added to SONAR via scans of the "VST Scan Paths" entered in Preferences > File > VST Settings
 
IIRC, the original Melodyne Editor may be a problem with X3 but this is a different issue.

No.  I had X1 on this machine in 64 bit mode.  I may have actually had 8.5 on this machine before that, but I'm not sure.  X1 in 64 bit mode for sure.  And I had Melodyne at that time.
 
Thanks.