start up error

I have Ubuntu 8.04
and when I start up my computer it says

Routine check of drives /dev/sda1
Press ESC to skip #'s% (stage 1/5 #'s/147)

then it says

cheking drive /dev/sda1: 11%(stage 1/5 25/147)
cheking drive /dev/sda1: 16%(stage 1/5 35/147)
cheking drive /dev/sda1: 20%(stage 1/5 43/147)
cheking drive /dev/sda1: 21%(stage 1/5 45/147)
cheking drive /dev/sda1: 22%(stage 1/5 48/147)
cheking drive /dev/sda1: 27%(stage 1/5 58/147)

/dev/sda1: UNEPECTED INCONSISTENCY; RUN fsck MANUALLY.
 (l.e., without -a or -p options)
fsck died with exit status 4
cheching drive /dev/sda: 30% (stage 1/5,63/147)
[fail]
* An automatic file system check (fsck) of the root filesyststem failed.
A manual fsck must be performed, then the system restarted.
The ffsck should be performed, in maintenance mode with the
root filesystem mounted in read-only mode.
* The root file system is currtly mounted in read-only mode.
A maintenunce shell will now be started.
After performing system maintenance, press CONTROL-D
To terminate the maintenance shell and restart the system.
bash: no job control in this shell
bash: groups: command not found
bash: lesspipe: command not found
bash: Command: command not found
bash: The: command not found
bash: dircolors: command not found
bash: Command: command not found
bash: The: command not found
root@Evo: #

can some one help me fix it??