What do these kernel error messages mean?

[Ross Boylan <RossBoylan@stanfordalumni.org>]

My logs show stuff like this:
Sep 16 07:51:30 wheat kernel: Directory sread (sector 0x19) failed
Sep 16 07:51:30 wheat kernel: Directory sread (sector 0x19) failed
...
Sep 16 07:51:30 wheat kernel: Directory sread (sector 0x20) failed


Sep 16 07:51:30 wheat kernel: t=12, limit=4
Sep 16 07:51:30 wheat kernel: attempt to access beyond end of device
Sep 16 07:51:30 wheat kernel: 02:00: rw=0, want=12, limit=4
...
Sep 16 07:51:30 wheat kernel: 02:00: rw=0, want=16, limit=4
Sep 16 07:51:30 wheat kernel: attempt to access beyond end of device
Sep 16 07:51:30 wheat kernel: 02:00: rw=0, want=16, limit=4
Sep 16 07:51:30 wheat kernel: t=12, limit=4
Sep 16 07:51:30 wheat kernel: attempt to access beyond end of device


I have not seen such messages before.  Can anyone tell me what this
means, and what my next move should be?

I have a feeling this is not good.....

Thanks.