Some of these..http://www.maplin.co.uk/cable-tie-bases-6235
stuck onto the kit to
allow cable tying might help.
If movement of the usb plug causes crashing it is
likely that the solder, or worse the track has cracked on the PCB. This had happened to my
Evolution Ekeys 49 (there is an M-Audio clone of it).
straight to PCB are always fraught this way, some connectors, jacks,XLR can be solidly
bolted to the front panel but I have never seen a "ruggedized" usb or FW connector?