The short of this error message is that SME disovered some serious problems with the Hard drive when it attempted to start up.
fsck is a utility for checking and reparing files that may currently be in a 'weird' state due to unexpected power outages etc.
(Unexpected power outages seem to be the most common cause for this situation.)
From memory, to run fsck all you need to do is type in something like:
fsck hda
(where hda is the file system you want check).
In this case 'hda', I suspect, is actually the file system you want to check as its the one that SME seems to be complaing about.
Regards,
Luke