Hmm, it looks like fsck doesn't pass the -b parameter through to e2fsck. Try running e2fsck directly:
e2fsck -b 8193 /dev/hda4

If that doesn't work, ask somebody else for ideas, as I'm out of them...
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Toby Speight
030103016 (80GB Mk2a, blue)
030102806 (0GB Mk2a, blue)