If you hit 'E' on your computer keyboard, to toggle the bypassing of all loaded effects plugins, does the issue go away?  If so, then one or more plugins are causing the issues.  (hit 'E' again to toggle effects back on).
 
Also, can you please detail which plugins you have loaded into a project that is having these issues?  Sometimes folks accidentally load a plug into a project that is meant to be used during mixing, when they are still recording, and issues result.  (when mixing, the ASIO Buffer Size can be adjusted way high, which allows consumptive plugins to be used, but too much latency occurs to do so during tracking/recording).
 
Bob Bone
 

I will try to get that info Bob. Again, it doesn't happen at all for me on Win8 and platinum.
 
Noel said he has seen it, but have not heard anything from him since. So it is a known issue.
 
I am back on Win8 for now. I may find some time over the weekend to go back to 10  if anyone has any other suggestions.

just confirming again that it is working in Win8 so far for about 2 hours this am.

I just wanted to report in here and say that it doesn't happen at all with my UCX (also over USB, latest drivers), Sonar Platinum 64-bit and Win 10. I do always make sure to plug my UCX into the same USB2 port (my computer has USB3 too and they do say it's supported, but still). I don't even have the very newest of laptops (quad core i7 2670 at 2.2GHz) but I can run most projects continuously at 64 samples. I know it's not an UFX but it seems close to it in hardware and drivers.

It's been rock solid so far. Only Melodyne related crashes here, as usual.

Windows 10, Rme UFX via Firewire (up to date drivers), Sonar platinum (latest revision). All good here. when the issue was happening, did you have the latest windows 10 updates? my computer is off line. Arthur 

I have had this happen to me with an LS 56, latest focusrite drivers and ........ W10.

It also happens when Sonar is not open but the machine has been idle for some time.

I need to check my power settings again, i have also heard that W10 updates revert certain settings back to default.

Cheers,
Jerry

FWIW, Running a Fireface UFX with Win10 here... with no such symptoms.
 
First, make sure all power-management is disabled (including USB selective suspend).
Also, go into Device Manager and disable power-management for each USB Root Hub.
 
 

I'm using RME UCX, sonar platinum x64, Windows 10.

The only time I have interruptions with mouse, USB hub, or interface seem to be related to update installations.

It would make sense that when idle Windows may attempt an update if update services are running. This could interrupt the RME.

If someone has a pc where the install was repeatedly being attempted and failing, it could maybe cause this case... ?

So, if you check the logs... application... For errors after the problem, do you find anything? Right click my computer choose manage and find the Windows logs. They take a minute to populate.

It doesn't happen at all with my UFX, Sonar Platinum 64-bit and Win 10 64bit Pro (with all latest Win 10 updates).

Hi. I am running a RME Ucx, latest drivers (USB), latest firmware, latest SONAR and Win10 X64 (fully up to date). I do not have any problems with the audio engine cutting out when leaving SONAR for hours, or even overnight. 
All the best.