Fsck failing with bit map complaints after long period

[Cal Thixton - President - ThoughtPort Authority of Chicago]

We have a 52gig raid5 setup and when booting, fsck can take quite a long time only to
eventually abort with complaints about bit maps.  Fsck gets up to 90% and slows to a
crawl with very infrequent disk activity.  Any ideas what is happening?

        Thanks
                Cal



Linux chilx1 2.2.12-20smp #1 SMP Mon Sep 27 10:34:45 EDT 1999 i686 unknown

raidtools-0.90-5

/dev/md0              52679028  30145640  19857380  60% /bigstorage

[root@chilx1 log]# cat /proc/mdstat
Personalities : [raid5]
read_ahead 1024 sectors
md0 : active raid5 sdd1[6] sdf1[4] sde1[3] sdg1[2] sdc1[1] sdb1[0] 53520192 blocks 
level 5, 16k chunk, algorithm 3 [4/4] [UUUU]
unused devices: <none>