Lots of people on the Rock Band forums are complaining of a pretty heinous multiplayer glitch in Rock Band 2, which seems to only affect the 360 version. In a nutshell, it strikes bands with Live Enabled gamers as the primary account, and non-Live enabled as the secondary. The glitch wipes out your band in tour mode, and forces you to start over. Particularly aggravating is that it seems to wait until you're a ways into the game.
Sifting through a 15-page thread I can't seem to find any response from Harmonix on this, as to whether the glitch is known, what the problem is, if there's a workaround, if a patch is coming, what. Now, I don't have a direct line to Harmonix — I don't even have the game here — and besides, it's a Saturday anyway. But yeah, if this problem is as people describe it, that's pretty goddamn aggravating and they're owed an explanation, or at least an acknowledgment of the issue. So how about it, Harmonix.
Email from a tipster explaining the glitch is on the jump.
Writes Justin B.
A number of Rock Band 2 players are experiencing an error in tour mode where at some point through the game (it seems people most often make substantial progress and are just prior to the aeroplane award) they start the game and find they cannot access their band. Your character and your band do not show up in the selection screen, but unlocked songs are still available. If you enter quickplay mode your character is deleted. For some reason your band will show up in online mode, but when you access it you get a message stating "looking for band leader" that never resolves and you have to back out. In the game options screen, when you try to load your band, or modify it in any way, you can still see the band but your only option is to delete it. This error seems to becoming more and more common, and its incredibly frustrating because your only option is to create a brand new band and start your tour all over again.
The common threads seem to be the use of an X-box Live Enabled primary account and a non X-box Live Enabled secondary account. To form your band. This makes me believe this will be an X-box 360 error and not anything that would effect the Wii or PS3 versions.