Problem: block on freelist isn't free

[Greg Carmack <carmack anthrasite com>]

Awakened to find 5.1 box crashed.  Attempts to straighten things out with
fsck.ext2 are failing, leaving system hung after reporting:
Pass 1: Checking inodes, blocks, and sizes
Problem: block on freelist at 0339cb10 isn't free.

I'm not having any luck finding documentation to help me resolve this.  Any
pointers to info, suggestions, etc.?
--
Greg Carmack  carmack anthrasite com
pager: 1-800-921-4674
PGP key: http://www.anthrasite.com/CarmackPUBKEY.txt