Constant USB/ASIO Driver crashes on UR28M


So my UR28M is a day old and installed. Trouble is, after every take, or if I do just about anything in Cubase (7.0.1) the output (or recording) stops on the UR28M. The only way to get it back is to do a hard restart of the UR28M - which reloads to the USB drivers etc…
I’m running the latest USB drivers/Tools from Steinberg and I’m on Mac OSX (10.8.2) on an iMac (8GB Memory).

What do I have to do to get this stable??? It’s virtually ‘unusable’ at the moment.

The UR28M is plugged directly into the Mac.

Any help gratefully received!!