Kernel Panic

[Shawn Badger]

Hi, I installed FreeBSD 7.2 Release on a mini nettop (Intel 
Atom/945gc/ICH7 hardware), and everything seemed to go smoothly. 
However, when I boot the system and the filesystem checks have been 
going for awhile, it always ends in a panic.  Here's the dump:

dev = ad4s1f, block = 1, fs = /usr
panic: ffs_blkfree: freeing free block
cpuid: 1
uptime: 15m47s
Physical memory: 2027 MB
Dumping 180 MB:

Fatal Trap 12: page fault while in kernel mode
...

I am using the default filesystem.  Does anyone know what might cause 
this, and how I can fix it? 

Thanks,
Shawn