do not reboot your machine anymore.
backup all that you can or want/need, soon.
The hard drive is on deaths door.
After you back it up, consider trashing it. If you really want to try and use it again, reformat the partition and have it scan bad blocks, but if you have a large hard drive, then it can take a long time ( like 24 hours or more). Out of three hard drives I tried to save, only one actually was saved, and even then, it completely died a few months later.
I've also had hard drives do that to me when there isn't enough power from your power supply. Why did you reboot? Did you add a newer power hungy video card? Add another nic card? Try unplugging a non essential device like a cdrom drive from power, and boot up your machine again and see if you still have errors.