Black screen when joining (N)L game with wrong char

When trying to join a NL game with a L char (or vice versa), the screen goes black and stays so for 20 minutes (!!). No, I’m not exagerating. I assumed you’d get back to the lobby after a while but after 20 minutes (was semi-afk) this hadn’t happened. So I killed the process and re-started d2r.
Clearly, the game’s handling of joining wrong games (this might affect classic vs. expansion and/or HC vs SC as well, I assume) needs to be improved.

err … how do you manage to join a game running a different mode than your character is in?

Trying to join a game in the wrong mode by typing it’s name and click “Join” results in a loading screen that does NOT load - the door remains closed - and after a while an error message stating “Login failed” before throwing you back into the lobby.

I couldn’t join. I edited my post. Hopefully it’s clearer now.

that’s what I accidently did. But there was no loading screen or error message or return to lobby. Screen went black and stayed so for 20 minutes.
That’s why this bug report.