i actually dont think this is line 6.. i had the EXACT same issues and i found a solution for myself so i figured i would chime in, maybe it wont work for everyone or it wont apply to you, but what i found was that the ux2 HATES usb 3.0 ports. sometimes, if in a 3.0 port (which is SUPPOSED to be backward compatible with 2.0), it will work great, sometimes it works for a half hour then dies, sometimes it doesnt even show up at all..the SECOND i put it in a 2.0 port...ALL my issues went away.
what im hoping is that some or all of you have been plugging it in to a 3.0 port...just switch it to a 2.0 and you should be golden :)..hope it helps
