Computer shuts down with elgato thunderbolt

I have to hook up my Macbook Pro 15" retina to 2 thunderbolt cables when working at home. The 1 thunderbolt goes to a monitor and the other thunderbolt goes to an elgato Thunderbolt dock (which connects to another monitor and other gear: audio interface).

My problem is that sometimes when I plug everything in and pound on the keyboard and mouse to wake everything up (after the monitors have gone to sleep from the previous day), nothing will happen.

I'll unplug, open the clamshell and the screen will be blank.

To get everything working up again I have to do a hard restart by holding the power button until it fires up with a 'there was a problem...' screen.

Anyone have any idea what's going on?

I ran a Techtool Pro scan but it found nothing.

Thanks