When trying to boot from the Mac OSX Snow Leopard install disk, it failed to boot which was not very surprising as the optical drive was old and designed for use with Windows. After this I restarted my computer, to see this message from Ubuntu.
/dev/sda2 contains a file system with errors, check forced. Inodes that were part of a corrupted orphan linked list found. /dev/sda2: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY. (i.e., without -a or -p options) fsck exited with status code 4 The root filesystem on /dev/sda2 requires a manual fsck
I have since removed the disk, unplugged the optical drive and restarted the computer multiple times, but the problem persists. What is the problem and how do I fix it?