unexpected inconsistency – redhat linux

Hi there,

I have a problem in booting up the linux system. I try running fsck and fsck -y /dev/sda but nothing happens. The error message that i get everytime i reboot are :

An error occurred during the file system check.

Dropping you to a shell; the system will reboot when you leave the shell.

CTRL D for normal bootup or Maintenace mode.

UNEXPECTED INCONSISTENCY; RUN fsck Manually

If anyone out there able to help me just reply to me please.

Regards,