Something since June 8th clobbers my disk...

[Dan Allen]

I sync with 7-STABLE almost every day.  I build everything on a  
Toshiba U205 Satellite.  Things are fine for months on end.

I did this on June 8th.  Everything was fine.

I did this on June 10th.  The machine no longer booted.  The entire  
root partition got clobbered.  I reinstalled a snapshot of 7-STABLE  
from May 28th that I had put on a DVD.  Everything was once again fine.

I then sync'd again this morning June 11th with 7-STABLE, did a full  
build, and reproducibly, BOOM - the entire root partition got  
clobbered.  Gone.  Again.  After the reboot it just comes up with:

BTX loader 1.00  BTX version is 1.02
Consoles: internal video/keyboard
BIOS drive A: is disk0
BIOS drive C: is disk1

and stops.  Nothing else is printed.  There is no choice of how to  
boot.  There is no files for me to send, no log files to inspect, no  
remnants.  I unfortunately did not see where in the build this  
happened.  My build does the canonical steps exactly as outlined in / 
usr/src/Makefile  and then does a reboot.  It builds userland and the  
kernel.

When I inspect it from the bootable DVD the partition that my root  
filesystem was in has no association with it having the root any  
more.  The partition is listed, but it looks like it had been freshly  
partitioned.

Something is very, very wrong.

Ideas?

Dan Allen