How to restart a freezed tty?

[Bahman M.]

Hi all,

For some reason all the ttys are frozen up; I can switch between X and
them back and forth but not between the ttys themselves using ALT+Fn.

I tried killing them; they terminate and restart but still
frozen.  I don't believe the only way out is to restart the system.

How to make ttys behave normally?  I'd appreciate any idea.
FreeBSD 6.2-RELEASE-p7 
xorg-7.2
fluxbox-1.0rc3_3

TIA,

Bahman