df -h returns invalid result

["Andrus Moor" <eetasoft@online.ee>]

I have a 2 GB ext2 root partition /dev/hda6 (only parttion with Linux).
I want to determine the available free space in this partition.

At boot time, fsck was ran and it reports that filesystem is clean

output from df -h is :

Filesystem            Size  Used Avail Use% Mounted on
/dev/hda6            -399548369317k  1.0k  0.0k  70% /
/dev/hda1              15G   12G  3.6G  76% /xp


how to determine the free space in hda6 ?