No playback on sonar x3

By any chance are you using the default Windows behavior with regard to your USB ports?  I ask, because Windows will after some period of time disable inactive USB devices.
 
You can check this by going to Control Panel\Hardware and Sound\Power Options, then select the High Performance plan, and then click on Change plan settings.  
 
Once in the Change Plan Settings dialog window, set it to Never put computer to sleep, then click on Change advanced plan settings.
 
In the Power Options dialog box, expand the USB Settings, and also expand USB Selective Suspend, and set it to Disabled.
 
While you are in the advanced settings dialog box, I also recommend you look for and expand (if you have it), Processor Power Management, and then expand Minimum Processor State and set it to 100%.
 
Make sure you save your changes as you back your way out of it all.
 
The above changes will tell Windows to run your CPU at maximum all the time, and will also prevent Windows from arbitrarily disconnecting any USB-connected devices, such as midi controllers and audio interfaces.
 
Also, sometimes Sonar does not wake up well, so it is best to not let your computer go to sleep when running Sonar.
 
Lastly, if you have any 'green' hard drives, this can really gum up the works too, for some reason.
 
Anyways, I cannot say if any of the above is what is causing your current issues, but is easy enough to check, and the above settings are in my opinion good to have set anyway.
 
Please consider applying the above changes, then post back with an update on your issues after the changes.
 
Bob Bone
 

Thanks Bob for the reply, I did everything you said, then unplugged & re plugged in the interface and everything is working fine, hopefully it will stay like that.
Thank you once again for your help, I will also post my system spec's 
 
Paul Carroll