Broken loader on 7.1-STABLE?

[Mark Kirkwood]

I wrote:
>  
> I am getting this too - update from RELENG_7 @12 Jan src to 20 Jan and 
> I have:
>
> panic: free: guard1 fail @ 0x511d
> from /usr/src/sys/boot/i386/loader/../../common/module.c:959
>
> Can't work out which disk we are booting from.
> Guessed BIOS device 0xffffffff not found by probes, defaulting to disk0
>
>

Forgot to say (cc'ing Luigi as he is collecting info):

Asus a8vx with an AMD 64x2 3800+ dual core