Hi all,
Every so often I lose connectivity to my Mackie control surface, which is connected via USB.  It's not a big deal, I simply reset the control surface input / outputs ports to MCU Pro USB 3.0 in preferences and everything works fine again.  But his happens fairly regularly regardless of driver versions on my RME UFX.  
 
Would this point to an IRQ conflict causing the USB connectivity to be intermittent?
 
Any ideas?
 
Thanks
Russ
 

Have you tried a different USB cable? The reason I ask is I notice whenever I run Sonar without my control surface plugged in, it also blanks out the settings in Preferences. So possibly having the connection physically broken due to a bad cable might have the same effect.

Thanks for the reply - I'll try another USB cable, although the one I'm using is new.. but will give it a shot.
 
Any other ideas folks?

A break in the physical connection is a possibility, hence the recommendation to try a new USB cable, which would address a broken cable but would miss bad solder joints in the boards at either end.
 
I assume you have disabled the power saving setting to automatically turn off USB ports.
http://www.techsupportalert.com/content/how-fix-annoying-windows-usb-problem.htm
 
An overload of the power supplied by the USB port is unlikely unless you have a toaster or coffee maker running off it  as well as your audio interface.
 
If this happens with any USB device, it suggests a problem with the USB ports on the computer. If it only happens with one device, it suggests that device may be at fault.

Slartabartfast - thanks, I'll doublecheck the power settings, but I'm 99.9% sure they're disabled.  (+ I have my UFX connected via USB, and those settings are never lost.. so I think the USB power is good). 
 
I have tried 2 different USB ports, so I was converging onto the assumption it was either the Mackie Control unit itself or something software related.

To second what groovey said, I noticed that if my Akai MPK 88 Pro is not connected when Sonar starts, the ACT settings are lost and I need to reconnect the outputs.

I get that too, not ev'ry time,  not a big thing but annoyin... , I have to close and reload Sonar.
It's just killing the work flow, when you jump in with fresh ideas.
 
I've check cables, connections, my daw is tweak to the max, no internet connect, a dedicated machine to music...
 
I always start the MCU before Sonar, 'cos the other way around, the MCU never work...
 
The worst in this, it's random... 
 
Rick

Yes, I always ensure my MCU is powered on before the PC running Sonar is fully booted up - so the MCU is always fully initialized before Windows and Sonar are running.....
 

In Preferences, under MIDI > Playback, maybe increase the size under "prepare using XXX millisecond buffers" to 500 or 750.
 
You also mentioned USB 3.0...I know USB 2.0 devices are supposed to be compatible, but I have run into occasional issues. If you have a "legacy" 2.0 port you might try that.