Thanks for the response, however I'm not convinced the Studio 192 is at fault.
It works exactly as expected for new projects, there's nothing wrong with it.  Sonar only locks up with old projects created with my old interface...
and if I disconnect the interface Sonar doesn't complain about silent busses,  it still locks up...

Sheanes
and you have your Midi device(s) with a Midi-USB converter conected to your computer and then set up in sonar as Midi device ?

All my devices connect with USB, using midi drivers.  Sonar sees them as midi devices.  I simply don't have any physical midi ports.
 
 

JonD
Just throwing some darts into the air.  Obviously feel free to ignore if you feel I'm way off-base....
 
Just to rule out that this one project is corrupt -- I assume you've tried to open more than one old project...?
 Yes,  they all lock up
MixControl -- Same version as before?  Was it completely uninstalled/reinstalled?
 What is MixControl?
Any other utility in startup trying to communicate with the 2626?
 I've deleted the driver, only Sonar running
If you're not using your firewire anymore, wouldn't hurt to disable the port.
 I can try that.

Karyn
MixControl -- Same version as before?  Was it completely uninstalled/reinstalled?
What is MixControl?

Oops, sorry, I was confusing Focusrite with Presonus.  (It's their driver software, but you said you already deleted the driver.  I'd look in Programs anyway, and make sure there isn't old software associated with the older unit).

It seems the more I try, the worse things get
 
I tried a total uninstall of the interface, Sonar complained that there was no interface then locked up.
I've reinstalled the interface, now Sonar won't open ANY projects..
 
I'm trying a rollback to Kingston,  getting really desperate...

You mentioned the Faderport dancing back and forth. In the past mine has done that too, and the project wouldn't load. Finally one day while the faderport was dancing, I grabbed the fader and moved it. When I did that, sonar popped up a window saying that there was a missing VST plugin. I clicked ok, and the project loaded fine. The missing VST had parenthesis around it. I deleted it, and never had another problem loading the project. So when the faderport dances, move the fader and see if you get a message.

I'm to tired to dance,  but I'll try anything...

Leadfoot
You mentioned the Faderport dancing back and forth. In the past mine has done that too, and the project wouldn't load. Finally one day while the faderport was dancing, I grabbed the fader and moved it. When I did that, sonar popped up a window saying that there was a missing VST plugin. I clicked ok, and the project loaded fine. The missing VST had parenthesis around it. I deleted it, and never had another problem loading the project. So when the faderport dances, move the fader and see if you get a message.

I WANT YOUR BABIES!!
 
When I grabbed the fader, Sonar popped up a window saying it couldn't find my old interface an asked if I wanted to assign those outputs to the new interface..
 
YEAHHH!!!
Saved the project, closed Sonar, re-opened Sonar and the project LOADS!!! 
 
Now I need a stiff drink...  I'll have one for you as well...

Glad it's working!

Nice solve, leadfoot! 
 
Two drinks max, Karyn.   Falling under the desk would defeat all of your hard work...

When I successfully help some one they say thank you. I must be doing something wrong!