e2fsck reports no problems, but mount warns of errors

[theclapp]

My system:

MyBook Western Digital external 1 TB drive, mounted via firewire.
Debian "stable" (mostly).
Linux 2.6.15, compiled locally

My problem:

Mount says "mounting fs with errors, running e2fsck is recommended"
Ran e2fsck (twice; took an hour each time), no errors reported
Mount still says "mounting fs with errors, running e2fsck is recommended"
dumpe2fs says "Filesystem state: clean with errors"

My question:

How to clear the "error" bit? Leery of using drive that doesn't mount cleanly.

Thanks for any help!

Update: Problem solved.

The first two fsck's I ran, which didn't solve the problem, but nevertheless appeared to run a thorough check, were:
fsck.ext3 /dev/sdb2
e2fsck -C 0 -p -tt /dev/sdb2

The third fsck cleared the error bit, I think because of the "-f" flag:
e2fsck -F -f -C 0 -v /dev/sdb2

Thanks anyway!