All of a sudden, this FreeBSD box stopped letting people login.

Does anyone have any idea why?
And how would I go in and verify the integrity of the passwd and shadow file, ( i know jack about freebsd, i dont even see a shadow file on the testbox i just installed.)

any ideas would be great.

even if we try to boot into single user mode, it still asks for root passwd and doesnt let you in.

must be a passwd file problem???