On a Fireface UFX using USB I do not get a disconnect message even when switching between projects at different sample rates. So I'm not sure if there is a difference between different RME devices or that part is firewire related. I had the default sample rate set to 44100 and loaded two projects one at 44100 and the other at 96K and switched back and forth starting and stopping playback. The device switched without causing disconnect messages - there was a pause of a few seconds while it reset itself.

So for me I am using the default MIDI drivers from WINDOWS for the AXIOM, maybe my USB cable got a small issue that turns up from time to time?  Maybe the MIDI driver on the USB port from MS is bad?  Or maybe my USB port is bad?
 
Interesting.
 
Jim

Hi Noel, I did get the disconnect message with my RME UFX in USB mode. I had the default 48k with an opened project at that rate. I opened a 44.1 project and got the disconnect message. They were only opened one at a time though.
 
If you can suggest a couple scenarios, I will try to go through them and report.

I do not see any disconnect messages with the UFX when loading projects with different sample rates. It makes no difference if I close one and open the other. It loads fine without the message firing.
I am running the latest RME firmware and drivers from last week in case that made any difference to this behavior.
The only time I see the message is if I turn off/on the device while SONAR is running.

I will try this in the am and report as well as making sure I have the latest and greatest drivers.

I just got this disconnect turning off the metronome on my new project without any wav or midi files.
 
I did a FILE/NEW and created it from a normal template default at 192k. I went into the metronome properties and turned off the metronome and got this error.
 

 
I get these quite frequently and appear out of the blue so it seems. I tried opening 192k, 44.1k and 48k projects, but did not get the disconnect message. I turn off the metronome and then get this quite unexpected. I guess when I ran into it the other day, it was a fluke.

Noel, Should I make another thread for this, or would you like to PM me?

I do not see anything like this with enabling or disabling the metronome. Its possible that you have the same issue that the OP had with a faulty cable or controller. To date I have never seen a spurious disconnect message from the UFX under USB and win8 so there isn't much more I can do to assist.
Keep in mind that Windows sends these messages after it unloads or reloads the device driver and there can be a brief delay before SONAR notices this message and pops the prompt. So the actual disconnect  might have occured before the most recent operation. 
Again I have to reiterate that SONAR itself does not disconnect the device explicitly. Accoring to RME the only ASIO operation that can cause the driver to unload and reload as a side effect is changing the sample rate. Although I do not see disconnection messages come through in this case, so either the driver doesn't unload always or the message is masked by windows somehow.

I have and use a recently purchased heavy duty and shielded USB cable. I know hardware goes bad, but i doubt this is.

I used to get these messages when I had my ff800 and different protocol cable too. I find it odd that 2 totally different hardware configurations get the same random message in the same software in the same studio.

I would like to not see the message, but the workaround is simple enough. I just hit No and proceed without issue.

It is still irritating though...