USB or FireWire?

What is shown in the Device Manager exactly?

When exactly do you get this error message? Did you try DIGICheck with Hardware level meters and via ASIO?

It could be that the newest version of the Fireface driver requires Windows signing. I encountered much the same issue as you when I upgraded from 3.118 to 3.119 - my computer could see my Fireface 800, but couldn't use it. When I reverted to 3.118, everything began to work properly once again.

I see that as of today, RME is still providing a link to 3.118 on their downloads page - give it a try.

It's not because of an incompatibility between Windows Signing and Bootcamp. In another thread - https://www.forum.rme-audio.de/viewtopic.php?id=24362 - you'll find the suggestion that Fireface Driver version 3.119 requires the system to have had Microsoft update KB3172605 installed which, among other things, will implement Digital Signing. KB3172605 has a prerequisite (it won't install unless you've already installed KB3020369).

There is an issue with KB3172605, in that it will disable Bluetooth if your machine uses Intel Bluetooth hardware (and drivers). If you don't need Bluetooth capability, then go ahead with this installation. Having these two KB updates installed will give you the added benefit of speeding up the amount of time required to scan for new updates when you run Windows Update (no more waiting hours and hours for the update scan to complete).

Here's a link to an online article explaining this situation in detail: http://www.infoworld.com/article/313667 … rever.html

Thankfully, Fireface driver version 3.118 is still available, at least for the time being.