On Wed, Aug 01, 2007 at 06:42:09PM +0900, Takahiro Kambe wrote:
> #0  cpu_reboot (howto=256, bootstr=0x0)
>     at /usr/src/sys/arch/i386/i386/machdep.c:856
> #1  0xc047e47d in panic (
>     fmt=0xc06deeb0 "pool_get(%s): free list modified: magic=%x; page %p; item addr %p\n") at /usr/src/sys/kern/subr_prf.c:243
> #2  0xc047bb10 in pool_get (pp=0xc07f9ca0, flags=2)
>     at /usr/src/sys/kern/subr_pool.c:1076

Are you by chance using NFS? I wonder if this is related to 
http://www.netbsd.org/cgi-bin/query-pr-single.pl?number=36424
(which I still can reproduce quite reliably, but have no idea what goes on)

Martin