Okay I'm sorry, the newest update for X2 is this. Posted March of this year.
 
https://www.cakewalk.com/...13301/SONAR-X2a-Update
 

Here's the latest drivers for your Audio interface;
 
http://www.rolandus.com/p...ua-25/downloads/ 

Here's an article you should follow!!!
 
http://thehub.musiciansfr...izing-windows-for-daws

Here's another;
 
http://www.presonus.com/n...7-for-Music-Production

Here's my last suggestion for the night.
Right click your speaker symbol in the bottom right corner of windows, then click on PLAYBACK devices then highlight each device in there one by one, then select properties, then advanced, then set every device to 24 bit 44100 hz then do the same for RECORDING Devices. Everything should always be set to 44.1 hz (44100) If one device in there is set to 48000 and your recording software is set to 44100 you will have all kinds of stupid problems like clicking and popping and audio drop outs. I did! until I changed all of them to 44100.
Man, that took me a lot of frustrating hours to figure out!!!! 

NumTarn
 I try to reduce it to the left and get an error message saying device in use by other applications..close down and restart..As far as I know there are no other applications "on"....everything is shut down?  

Do you have system audio/sounds routed to the UA-25? 

Maybe I missed this from earlier posts, but do you happen to have your audio interface also set to be the Windows Default Audio Device?
 
If so, and you are running ASIO, then anytime Windows wants to play any windows sounds, it will compete for control of the ASIO drivers, as only one application at a time gets control of it.
 
IF you DO have it set that way, try altering it so the Windows Default Audio Device is set to the computer's internal sound chip/card, and see if that stops at least that error where Sonar all of a sudden cannot see the audio interface.
 
Bob Bone
 

When I go to the ASIO panel , press the button,move the slider to the left ...an error box says.."device in use by another application. To have changes take effect, Close all applications and restart Sonar"??  Problem is I dont have any "other " devices enabled that I know of?   Only Sonar is on ? 

As I had indicated to you in response to your private message, even if no other applications than Sonar are running, WINDOWS could still grab exclusive control of your Edirol audio interface, IF Windows is set to use the Edirol audio interface as the Default Audio Device.
 
In simple terms, generally speaking, the ASIO design specs are that only a single application can have control/access to an audio device, using ASIO drivers.  SOOOO, this means that if both Sonar and Windows are set to use ASIO drivers of the audio interface, there is an inherent conflict potential that way.
 
I believe it probable that you have both Windows and Sonar set to use ASIO of your interface.
 
You can click on the little speaker icon in your system tray (bottom right corner of your screen), and Windows will display whatever is the currently set default audio device for Windows to use.  IF you have this set to your Edirol audio interface, then I recommend you change the Windows Default Audio Device to use your Realtek drivers for Windows, and then leave Sonar to continue to use the Edirol audio interface with a driver mode of ASIO.
 
Please try going into Control Panel and changing the Windows Default Audio Device to be the Realtek on-board sound chip in your system, and then see if that fixes Sonar.  Let's start with this and then we can figure out how to also deal with hearing your Windows sounds outside of Sonar AFTER fixing Sonar first.
 
Bob Bone
 
 

Hi Bob,
Thanks for the comprehensive advice. I think its very good...and you are probably right  The problem is I cannot change the default device. In Manage Audio Devices ONLY EDIROL comes up..If I right click "show disconnected devices" it brings up the High Definition Audio device (with a red cross on it ) - greyed out ....I cannot make it the default as its greyed out.... It appears to be there as I have played a track and monitored it via the headphone output on the pc...but not enabled?...I have tried to enable it..   This should not be that complicated, but until I am able to assign the Realtek as the default audio device I cannot test Sonar for latency....I will try again later today
Cheers,
Ross