Can you boot into single user mode?
While starting up hold down the Apple key + "S".
Then when all the text scrolls by and you get a cursor type in:
/sbin/fsck -y
If it reports that your Harddrive was OK, then type in:
reboot
If the process notes, that it changed your drive then rerun:
/sbin/fsck -y
basically keep running it, until all the problems go away.
Good luck,
and keep up posted,
t