Can someone please explain to me what the hell is going on with Backtrack.

I have tried two very much different versions of BT5, and the problem is present in both of them.
- 64 bit Gnome version installed on 10GB ext3 partition on disk1.
- 32 bit KDE version installed on 10GB ext4 partition on disk2.

Here is the problem:

Short time after installation and completely normal work (configuring, scanning and some light stuff) Backtrack fills the HDD with unknown data.

Kdirstat and Baobab show only 5 GB occupied by files, but the disk is completely full. Nautilus shows that some data is unreadable but Fsck says filesystem is OK.

Looks like space is allocated beyond FS recognition, or to put it that way.