I am using a Plugable UD-3900 docking station with my Dell Inspiron 7506 connected to connect my external monitor, speakers, and mouse and keyboard with a unifying USB receiver. The external monitor is connected to the UD-3900 with a DVI cable.
The link between the docking station and laptop gets lost many times each day. I can re-establish the link by toggling the power to the docking station. However, this is very frustrating because everything open on my external monitor screen moves to the laptop monitor during the lost connection which then requires me to move the program screens back to the external monitor.
I make sure the drivers for all devices, including the Plugable drivers, are kept up to date. I had the same problem with another laptop, a Dell Inspiron 7559, which I used to use with the UD-3900.