I was also extremely pissed that Symphony X didn't play. I spent $111 on two tickets and drove four hours each way, which I probably wouldn't have done if I'd known SX wouldn't be playing, but Dream Theater still kicked major ass, so it wasn't a total loss. Also, I hadn't previously heard Nevermore, and I kind of dug them, so I bought their CD and got to meet them. Still I talked to a few people who got there, found out Symphony X wasn't playing, and left immediately. I'd have been one of them, if not for DT. It may have been out of the band's control, but that doesn't mean you can't try to get your money back from Ticketmaster or the venue itself. Seems fair to me, unless there's some kind of TOS you agree to just by buying a ticket, that says they can change anything about the show and don't owe you a refund. It's worth a try, though.