Extremly interesting df output. Help, please.

[Александр Деревянко]

Hello All !

I'm using FreeBSD 5.4.

Today i have received daily output from my home computer.
That's it:

Disk status:
Filesystem  1K-blocks            Used          Avail Capacity  Mounted on
/dev/ad0s1a    253678           36946         196438    16%    /
devfs               1               1              0   100%    /dev
/dev/ad0s1d   9206302 -17592178674642 17592187144440 -207704820%    /usr

Immidiatly, i have connected to it and see the same numbers in df output.
Yesterday output is OK.

Yesterday the computer rebooted spontaneously, and processed with background fsck.

Does anybody have the same expirience?

Best regards,
Alexander.