Help! Hard disk problems

[Anthony M. Agelastos]

Hello all,

In doing some routine items on my FreeBSD box, it started behaving  
oddly. I rebooted and to my surprise, I started receiving many  
messages displaying information regarding that /usr has issues. It  
puts me directly into single user mode and tells me to run fsck  
manually. When I run fsck all by itself, here is what it tells me:

** /dev/ad0s1f
** Last Mounted on /usr
** Phase 1 - Check Blocks and Sizes
UNKNOWN FILE TYPE I=496000
UNEXPECTED SOFT UPDATE INCONSISTENCY

CLEAR? [yn]

This is the first time that I have ever run fsck and I have no idea  
what this message means or what the best course of action on CLEAR to  
take. Any input at all would be greatly appreciated (FreeBSD 6.0- 
STABLE if it helps). Thank you all so much for your assistance.

-Anthony