I just read some old tmp problems threads. it seems developers just reply these
are internal files and should be deleted !
if it is the answer please tell me where has all this 10GB of data gone ?
There is something really wrong with httrack.
I am sure all the tmp files which I viewed were complete. and had </html> tag
in the end of them. seems httrack could not detect the download is complete so
it has treated them as unfinished and deleted all 10GB of completed data.