I recently have encountered a problem that I can't seem to find a solution for: When I start Sonar 8 I get a pop up that says that my Roland UA-25EX 24 bit audio interface "device" does not support the audio format or is currently being used by another program. The audio format in Sonar is set to 24 bit and In task manager I don't see where he device is running elsewhere.

This device worked fine (for years) up until yesterday - the only thing different - I unplugged everything from my computer so I could move it to a different area of my home studio - then plugged everything back in as before. Any ideas?

Hi. Could there be a mismatch between samplerates / bit depth? Do you have the latest updates to your Audio Interface, and windows? The more info you give, the easier it is to troubleshoot.
Ps. Do you you use the ASIO drivers that came with it?
Best of luck.

Have you disabled System Sounds robbttt? Worth checking they have not been re-enabled. Windows may be using the UA-25 for those and messing with your sample rate.

If you plugged your audio interface into a different USB port when you reconnected everything, it is possible that the drivers won't function properly.
 
If you aren't sure which port is the 'correct' one for it, you could try uninstalling and than installing the interface's drivers again, and perhaps make note of which port you have it in, for next time.
 
This used to happen with me and a Native Instruments Kore 1 audio interface.  It does not happen with all makes/models of interfaces, but is easy enough redo the drivers to see if that fixes it.
 
And, if the Windows Default Audio Device is set to your audio interface, then Windows and Sonar may well fight over who controls the ASIO drivers - this is a fairly common thing - lots of folks turn off Windows Sounds, and many set the on-board sound as the default audio device in Windows, and keep the interface for exclusive use with programs like Sonar, to avoid any conflicts.
 
Bob Bone
 

+1 to Roberts post. Always use the same port. I mark mine with a Sharpie. 
Either find the port you used before or re-intall the drivers. 

Your computer is finding the Roland interface or you wouldn't be getting a popup that mentions it by name. Before you uninstall/reinstall I suggest you take note in Sonar of your bit depth and sample rate settings, then close Sonar and any other audio programs, open the Roland driver controls and set it to match Sonar. Then try Sonar again.

Disconnect the device from USB, wait a little while and plugin it back in.Windows will say it's found a new device and ask to install the driver. Follow the prompts.

You knocked the Advanced Driver switch at the back to OFF.

have the same message frequently, haven't found a 'fix' but I don't really bother.
it happens sometimes when I use Internet or other programs that play audio, and then open Sonar later.
(I have a low buffer size, high sample rate in Sonar....I'm guessing it's one of them causing it).
I just quickly shut down all the programs and interface, then after restarting it's ok.
 
Then I check in Sonar under Edit/Preferences/Driver settings....sometimes I have to reset 'sample rate' and under 'Asio panel' reset my buffer size of choice.
So basically I think you would need to check above settings only, whenever you have this error.
(On my machine this is not related to changing USB ports, tried and did not make a difference, and it's not related to bitsize 16 or 24 as far as I could check)
good luck

robbttt - It would be great if you'd come back and let us know if any of these suggestions worked for you, or if you found a different answer to your question.