fsck problem FreeBSD 8.3

[Коньков Евгений]

Hi.

Apr  9 19:51:58 fsck: /dev/ad8s1e: UNEXPECTED INCONSISTENCY, CANNOT RUN FAST FSCK
Apr  9 19:51:58 fsck:
Apr  9 19:51:58 fsck:
Apr  9 19:51:58 fsck: /dev/ad8s1e: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY.
Apr  9 19:51:58 fsck: /dev/ad8s1e: CANNOT SET FS_NEEDSFSCK FLAG
Apr  9 20:09:22 kernel:

running manually:
# fsck -y /dev/ad8s1e
** /dev/ad8s1e (NO WRITE)
** Last Mounted on /tmp
** Phase 1 - Check Blocks and Sizes
** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
** Phase 5 - Check Cyl groups
99 files, 10 used, 506477 free (45 frags, 63304 blocks, 0.0% fragmentation)


Server reboot two or three time per day
# uname -a
FreeBSD flux 8.3-PRERELEASE FreeBSD 8.3-PRERELEASE #3 r231881: Fri Feb 24 17:07:48 UTC 2012     adm at flux:/usr/obj/usr/src/sys/KES_KERN_v8  amd64

before this it works about month without problems

/var/crash - empty, in /var/log/messages there is no any messages before crash.
Can any help to fix problem?