Disconnect your UX2 from the current USB port you've been using. Then, find a new direct USB on your computer that you've never connected before to and use that. You may need to go through the USB Device Driver wizard if you're running on Windows XP. Otherwise, Vista and Mac OSX should run that process transparently.
See if another physical USB port provides correct connection/functionality. You may need to try a different USB cable, too. Beyond these suggestions, a reinstall of the USB driver software using Line 6 Monkey wouldn't be a bad idea either.