I'm just responding in kind - I'm not taking it personally :-)
'Application not responding' is new info - sounds like it doesn't like this particular disk for some reason.
Terminating the process (and pulling the plug) with extreme prejudice is unlikely to have helped though I'm afraid.
Something's causing Finder to hang, and your best bet in these situations is to command-option-escape to bring up the equivalent of Task Manager which may allow you to relaunch the Finder when the Dock-icon menu doesn't.
I'd shut the Mac down, re-plug the USB disk with a different cable and reboot with it already connected and see if that improves things.