After complaints from my users that windows wouldn't let them log
in (domain controller from samba) and that YP/NIS and NFS wans't working anymore I tried to ssh into the server but that didn't go either.

Nothing seemed to work anymore so I rebooted it and attached a monitor,
then I saw that suddenly the root filesystem (/dev/hda3) was mounted
read-only.

It refuses to mount /home, /boot,/proc and the likes.
Remounting after boot (init 1) works ok as far as I can see,
booting off a resue disk and chrooting in works ok, fsck says the
partition is ok, so why gets it mounted as ro on boot?

Server is debian stable on linux 2.4.24 running services as NFS,samba,NIS,...

Any input greatly appreciated as usual.

What is the entry for the root filesystem in /etc/fstab?
Can you remount the root filesystem as read/write? Do you get errors on doing that?

Remouting went ok as I said earlier.
Turns out the problem was something else...
That stable box was once updated to testing by accident,
it was downgraded again, but never rebooted.
So everything went great untill today; new kernel and reboot.
The wrong init scripts were loaded and that caused the / partition
to mount as ro. (guess the downgrade wasn't succesfull).
I did a force-overwrite on the sysvinit package, rebooted and everything
is ok again.
Took me a while to figure that one out