I haven't plugged my laptop into my Toshiba Dynadock U port replicator for a while. I plugged it in recently and the "Add Hardware" notification popped up. This was a little disconcerting because my laptop has been connected to the Dynadock hundreds of times before. Anyway, since that time, I'm getting no video. Here's what I've done:
Verified that the monitor is functional. It works fine when connected directly to the laptop.
Verified that the Dynadock is non-functional with other monitors.
Installed the most recent Dynadock U drivers on my laptop (A Dell Studio 1500.)
Played with the "Extend Display" functionality a lot. (I've extended the display and duplicated the display. Nothing works.)
All other functionality on the Dynadock works (NIC, mouse, keyboard, audio...)