Greetings.
I hope this saves someone from the frustration I had the last few months.
My Setup:
Lenovo Thinkpad Helix
Windows 8.1 Beta with latest updates
Lenovo USB 3.0 Dock
2 displays connected via DVI @ 1680x1050 each
LAN and audio connected to the dock
DisplayLink 7.4M0 driver and recent firmware (checked Hardware ID from USB Hub)
I ran into some serious issues with this setup as the Dock kept disconnecting up to 10 times a day, just for a few seconds.
Sometimes it was just a short flickering on the displays, but sometimes the displays went completely black and I had to shut down my thinkpad and also restart the dock.
The workaround for all problems was very simple. A few days ago I started connecting my speakers directly to my thinkpad instead of the dock.
Since then there has been no single incident! The dock just keeps working.
TL;DR
Disconnect your speakers from the dock and connect them directly to your notebook/tablet and the dock connection issues may disappear.