Hi,

Please post what distro you are using, when exactly the error occurs, if it causes any other unwanted activity, how long you have been receiving this error, if you know of anything you have done immediately prior which may have caused the unwanted activity, etc..  We want to help, but we have no precognitive powers, so the more information you provide the more it helps us help you

Do you get this error message when booting up the machine?  Despite the error, does the machine then boot up properly, or is some other problem present?

Sorry, I did not understand you if you were able to boot all the way or if you only get to the grub bootloader.
 
I guess that something got tweaked with your filesystem, most likely either a power failure (suggest you use a UPS battery backup) or from hacking.
 
If you ARE able to boot up all the way or get to shell prompt, go to command line and tell me the output for the command "df" and also for "fdisk -l". Paste the results here in reply.