I am on HP 320 on 12/29 PHL>LAS. The flight no longer shows up on the US Air website, and seatcounter comes up all red zeroes for the flight. This happened earlier today, then mid-day there were many 4's for the flight, and now it is back to all zeroes. Does this mean the flight is sold out/overbooked? I'm trying to prepare myself in the hopes of getting on a different flight......