Here’s a quick fix for an Ubuntu 10.04 bug that prevents USB Drive from mounting on a PC with Floppy drive (wow, these things still exist?)
The solution is to remove the floppy drive module from linux kernel and you will be able to mount usb drive.
sudo modprobe -r floppy
Should you ever need the module again, you can issue
sudo modprobe floppy
to load the module back (alongside with the annoying bug).
Hope this will help!
p/s: To be fair, my office Dell Optiplex machine (with Pentium 4 HT 2.80GHz, 2005 issue) still has those floppy drives, although I haven’t use them ever since they assigned it to me (back in 2008).