[KLUG Members] weird df output

[Adam Tauno Williams]

> Has anyone ever seen anything like this?  Everything seems to be 
> running ok.
> mail:/# df -h
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/hda5            -303426204464k  1.0k  0.0k  49% /
> /dev/hda1            -20410801940k  1.0k  0.0k  21% /boot
> /dev/hdb1            -1099314459551k  1.0k  0.0k  28% /mnt/bdrive
> mail:/#

Is this is a Linux box or some other kind of UNIX?  I've seen this using
the GNU version of df on AIX,  the key is that the Use% is right while
the presentation of the other columns is mangled.