2.5.x / shutdown -r now doesn't

Whee...

This has been happening for a wee while now (basically ever since I moved to 2.5.x I think but I don't use shutdown -r now often). Essentially, when I do it, the laptop goes through the motions, the kernel (I assume) says 'Resetting System...' (or Restarting - not too sure) and then turns itself off. When I do ctrl-alt-del it reboots just fine. I'm using ACPI if that's of any help.

        All people are equal,
        But some are more equal then others.
            - George W. Bush Jr, President of the United States
              September 21, 2002 (Abridged version of security speech)