My old interface died (Firestudio 2626) and I've replaced it with a Studio 192.
 
I can create new projects ok, they save and load perfectly fine,  but old projects (created with the Firestudio) refuse to load leaving Splat "not responding" and the only way to kill it is with task manager.
 
Yes, I've tried opening in safe mode and saying no to every plugin,  doesn't help.
 
The only difference I can see is that the Firestudio had built in MIDI, whereas the Studio 192 doesn't.
I guess it's something to do with the midi because it turns my Faderport (connected with midi) into a dancing disco...
The physical audio outputs are in a slightly different order, but they're all there and enabled in Preferences.
 
Is there anything I can reset?  ini file I can delete and rebuild?  I've tried turning off ALL midi ports and once I get past the many warnings that there are no midi ports it still does the same (locks up opening old projects (but without affecting the Faderport which now has no midi))
 
I'm getting desperate now as I've a project to complete with a deadline of next Friday...!!
 
 

rename the aud.ini associated with your version of sonar to aud,old and restart sonar?

It could be a hidden window asking for input that is the problem. If you are on Windows 10 use (Windows key + tab) to see all the open windows. 

Similar to this?
 
http://forum.cakewalk.com/New-Interface-vs-older-projects-m3349573.aspx
 

Maybe a full repersonalize by holding the CTRL+SHIFT while starting SONAR. This will reset some registry entries and overwrite your user directory including AUD, Cakewalk and TTSEQ ini files. You may want to copy your existing user directory somewhere if you want to recover customization.

It's similar in that I've got a new interface, but I can't load any projects created with the old interface, even in safe mode.  Sonar seems to go into a recursive loop and the only way to kill it is with task managers "end task" command.
 
No John, there are no hidden dialogue boxes...

I don't bother with customisation scook.  I'll give that a try...

Nope, still locks up....

Does it lock up if only the audio interface is connected to the PC? IOW, disconnect the faderport and any other other MIDI devices from the PC, reboot and launch SONAR.

I just renamed aud.ini and now a new project that was working won't load either....
 
I'll try disconnecting everything...