R/W mount of / denied

[Lutz Petersen]

After a system crash (e.g. a power failure), the terminal-less FreeBSD 
5.2.1-RELEASE I run does not boot up properly any more. Here is an 
excerpt from /var/log/messages:

Jul 25 20:18:04 server kernel: Mounting root from ufs:/dev/ad0s1a
Jul 25 20:18:04 server kernel: WARNING: / was not properly dismounted
Jul 25 20:18:04 server kernel: WARNING: R/W mount of / denied. 
Filesystem is not clean - run fsck
Jul 25 20:18:04 server kernel: WARNING: R/W mount of / denied. 
Filesystem is not clean - run fsck
Jul 25 20:18:04 server kernel: WARNING: /home was not properly dismounted
Jul 25 20:18:04 server kernel: WARNING: /tmp was not properly dismounted
Jul 25 20:18:04 server kernel: WARNING: /usr was not properly dismounted
Jul 25 20:18:04 server kernel: WARNING: /var was not properly dismounted

As a result, BIND does not start up any more, which leaves my FreeBSD 
box in an unusable state (no internet connection, no network connections 
that use DNS). I did not experience this behaviour with 4-STABLE. What's 
wrong here?

The other day I read about a misconfiguration of /etc/fstab (wrong 
fs_passno), which prevented FreeBSD from doing the usual consistency 
checking at startup time. My fstab is looking fine however.

Any help is greatly appreciated,
Lutz