The USB drive happends to be my Mem Map Adventurer 3500. It had a firmware upgrade (done by mem map under warranty) a few weeks ago. In the process of that, they wiped my maps off the unit. Reconnected it to my PC this evening to transfer them back, and nothing is visible. The closest I get is the Device Manager showing a USB Mass Storage Device with a little exclamation mark on a yellow diamond icon.

Updating the driver doesnt do anything, uninstalling and reconnecting takes me back to the the same situation, even with a reboot (although it does see there’s something there when first reconnected, then stops)

I’ll be emailing Mem Map for help, but if anyone has ideas, advice is greatly received. I could do with it working by tomorrow night for the wednesday night ride going exploring new places…

Make sure you’re plugging it directly into the pc and don’t use a usb extension cable.
Have you not used it since the update?

yep, direct into the PC USB socket, as I always have.
And no, this is the first time I’ve tried connecting it. I did try to use it once, which was when I discovered my maps had gone. Luckily, I wasn’t in the middle of nowhere at the time!