I've tried searching for similar subject lines, but found nothing of use.  
 
The project was originally created with sonar 8.5.
 
It was edited with sonar X3 using only the record function - no X3 specific Pro Channel or Effects - just DI Bass, but when the project was reopened with 8.5, Sonar application just appears to hang. No indication of what the fault is. Double checked the bit depth on all the recorded wave files and found them ranging from 16 to 32 bits.
 
Potential issue could be that the X3 Sonar instance was a 64-bit operating system and Sonar was installed as a 64-bit application, and the original project files were created on a 32-bit operating system platform, which is where we're trying to open them back up.
 
X3 config is in my sig.
 
Have tried using safe mode to open the project on the 8.5 system, but the results are the same - Sonar opens and simply does nothing.

Any suggestions?

Is there a particular reason you need to open it in 8.5? The obvious answer would be to carry on working in X3.  Perhaps the prochannel has a bearing on it?
 
If safe mode doesn't work I don't know what to suggest. I rarely if ever go back a version but if I do open an old version project in a newer version I save as straight away so the original is still there. I guess that may be a little late for your case though.

I'm missing the logic as to why to do this.

CW is great at making sure new versions are backward compatible. However. no one can predict the future and have forward compatibility. 

I would prefer working in X3, but my collaborator hasn't been able to afford it yet.
Thanks Karl

When opening the Project in Sonar X3 and saving it you converted it to a X3 project, doesn't matter what you did.
8.5 cannot open X3 projects (not backward compatible)... as far as I know???
Revert to a backup assuming you took one, otherwise you are going to have to get into messy exporting.
 
Any real reason why are you reverting to 8.5?
 
Cheers..

8.5 generates a message warning that the project has been edited with a newer version of Sonar.  The dialog box has the helpful "OK" button.  Pressing "OK" (as that is the only option) causes the hang.
 
I tested opening the project on my laptop - which still has 8.5 on it and for me, the dialog is followed by successful opening of the project.  My laptop is W7/64 Home.  My DAW is W7/64 Enterprise.  My collaborator is running W7/32 Pro.  My assumption is that the OS difference is causing the problem.  I just can't find a way to "save-as" the CWP to default to 32bit OS on my X3 Sonar instance.
 
Thanks all for the questions and helpful replies!
Dan
 

Ah ha!
 
Please check here:
http://www.cakewalk.com/Documentation?product=SONAR%20X3&language=3&help=Troubleshooting.29.html
 
Thanks...
 
(Edited)

I wouldn't have thought the x32/x64 would be a show stopper and as far as I know a project is a project. If OS type was an issue that would affect an X3 x64 project being opened in X3 x32.
 
Having said that I have no idea what else might be causing it.
 

You may want to try saving the project using the 32bit version of X3. Both 32bit and 64bit version may be installed on a 64bit host. No guarantee it will work though, I don't believe it is a 32/64bit issue. Still no harm in trying.