I have a nearly new Dell Inspiron 15 7000-series laptop. I also have a D3100 USB3 docking station. The dock has a monitor, speakers, mouse, keyboard, and disk drive attached. All was working fine for weeks. Just a few days ago, the speakers stopped working. Sound is now coming out of the laptop speakers even when the laptop is docked. In the Device Manager, when it is docked, there is a USB Audio device that has an exclamation mark on it. (E.g. isn't working.) I've tried updated the audio driver through the Dell support site. No improvement. I then found the latest driver on dell.com for the D3100 dock. I tried installing it, but it was refused, saying that the existing driver was up to date.
The speakers work fine when plugged directly into the laptop audio jack. E.g. there is no problem with the speaker hardware.
Any ideas how I can get the dock audio working again