if you're 100% sure it's the UX2, then you have of course still got another 2 months of warranty left (it comes with 90 days) so you've definately not wasted your money even if it is faulty.
it's the times we live in, all electronic devices are built well these days, but there's always a risk of getting a bum one. sure that's a right pain in the *** for you right now, but just get in touch directly with your nearest service center and they'll sort it for you: http://line6.com/service_centers/
might just be worth checking it on a different PC, or with a different guitar cable first though, just in case. or at least testing your guitar ans guitar cable with another amp, as I think I've had more problems with guitar wiring and faulty buitar cables over the years than I've had problems with Line6 gear.