wpdavids,
I would say that if you have looked thoroughly through the / filesystem and can find nothing that is causing this problem, it could be the following:
You had a file constantly being updated i.e. syslog in the root partition. Someone deleted the file without first stopping/killing the process - this means that although the file has been removed the i-nodes are still being updated and thus filling up the filesystem - an fsck will fix this but you cannot unmount / ,obviously - so I would recommend a reboot.
To see if this is the problem do the following:
You can do an fsck of the root partition now - if this is the problem you may get bad i-node map errors:
i.e.
fsck /
If you do not get these errors then this may not be the problem - but if you do you can only do a reboot to sort:
Cheers
PSD
HAMCP Specialist