Mpc studio USB to MacBook

Having a strange problem with my mpc studio.
When I have my MacBook turned off and the studio connected by USB and then turn the mac on, I can start up the mpc software and the controller is recognised.

Then the problem starts.....
If I disconnect the controller from the USB port then plug in again the controller is not recognised. A reboot with the controller connected is the only way to resolve this.
The exact same problem arises if I put the MacBook into sleep mode, when it wakes the controller is not recognised.

Anyone seeing this issue?
It's a real hassle to have to reboot the mac every time I want to use the mpc studio controller!

Are you running the latest OSX or at least an up to date Mountain Lion? I know there was some issues with audio cards and controllers with USB 3.0 until an update......

My Surface Pro 2 only has one USB port, and it is 3.0.... Running Windows 8.1 and cant use the Ren's audio, have to run it with ASIO4ALL..... It's a Win 8 issue with USB 3.0, that is still not fixed.... but it is fixed on the Mac, and the Ren works fine on it...

Back to Mac.... I run a fully updated Mountain Lion, and both Studio and Ren work fine....

Some questions arise:

1. Did turning the Studio off and on again change anything?

2. Are you running the latest firmware and software version?

3. Could you tell us what system you're on? iMac, MB Air etc..., RAM, CPU & interface maybe?

1. No change
2. Yes
3. MacBook Pro 2011 model. No issues with any other controllers.

I have the latest mounting lion installed.