The joining/leaving can be attributed to;
A room just opened with the host still in the room settings page,
A room that has started a game and is counting down,
A game that is in the process of loading,
A game that is "in flight".

This only happens to me sometimes when trying to join a random host from the game search. Its never happened when I've been invited to a friends game. So I assume its a small bug in the game search. Often when its forced me to leave and I try the same game again straight away, I get in.

No I'm pretty sure the times Ive been made to leave a game and I can see in the background the names of the people in the lobby, then I try again and might get in with the same people in the lobby. The game is not started and has already been setup with people waiting.

What I see in the background will be a game with several people in the lobby, but not full, that hasn't started yet. I get it maybe two times or so a night (I'm not online too much yet, much single player left to do). It probably annoys me more because finding a game can take awhile anyway, so finding one you can't stay in is just cruel ;)

@ Both above;

Both of the things your describing can happen when the host is has started a game and its counting down. He can then cancel the countdown, and then you would be able to join the game. I myself have done it a few times while hosting, starting a game and canceling due to some players leaving during countdown.

You have to have some team effort to bring them down, the b17 gunners are leathal at least for me the times I had a go at one with my bf109

Im more mad at 3 minute strike games for the kiddies who badly want their b17's and ghost games that doesn't exist but the online interface says is still in the lobby phase

i find the best way to take them out is an almost head-on pass. With luck and and some gunnery skills you can take out the pilot much easier than the actual plane is to destroy.

Really? nobody has ever taken down my B-17 by taking a head on pass (well unless its a kamikaze mission)

The ONLY plane that i have recognised to shoot me down was a BF-109 G6

2 machine guns and 3 cannons! thats your best odds at shooting one of the B-17's down

Ah yes! that explains it perfectly. Thanks :)

I suppose it depends on your mode. Arcade its harder to kill the plane imo since all planes are pretty tough anyway. The head on pass works pretty well there. It would probably be a lot easier in Sim mode with a competent pilot in the attack.