Does anyone else get that slightly empty feeling, when you've wasted an hour or two filling one in, check it's right, and then think: "Well, what was the point of that?"

And then try to find another to start!

open mike & leeneia - you're supposed to end up with a grid in which each line across contains the figures 1 to 9, each column up and down contains the figures 1 to 9, and each of those internal squares contains the figures 1 to 9.