Maybe alu's not having the same issue that I had, then. But it still sounds like a permissions problem. Are you using the default auto-login method?
no, I remastered. I don't know if that makes a difference. I ran an old copy of tc_1x with autologin, and got a slightly different mixture of tty permissions: tty0 and tty2 were tc:staff, and the others were root:staff. I guess it (tty1) adjusts to whatever is needed for the initial login.
I can experiment with different logins, since I don't have a clue as to how it works.
edit: I reproduced the error by logging in as "root", which gives /dev/tty1 permission of root:root that screen doesn't allow without X ( error: cannot open terminal /dev/tty1). If I login with any other local user, it's fine. The problem only occurs without X.
(note: I guess the auto-login is root, as you said).