This one is painful. I have a little gadget on my Ubuntu 8.10 laptop that shows the current CPU speed as part of my power management set.

A few minutes ago I noticed it was running 100% while idle, even though I've got it set to use power on demand. I fired up "top" and saw "dd" using 100% CPU. A little more digging showed some serious errors in dmesg about kernel panics.

A bit of Googling showed a kernel bug that causes it. Unfortunately I'm 2 revisions beyond the version cited in the bug and it still exists.

The workaround? Disable sysklogd.