checking multiple songs in iTunes

I don't know how to un-check multiple songs at once, but why don't you create a new playlist, select all the songs you want on your iPod and drag them in to your play list.

To create a play list click on the '+' sign on the bottom left corner of the window.
Multiple songs can be selected like in the finder by using the 'Shift' key or the 'Command' (?) key.

 

That's what I usually do. Those little selection boxes are more of a nuisance then anything. They would be useful if they were slightly larger and there was a way to deselect/select groups of them at once through a key combination or something. I've looked and looked and looked for such a key command but I am afraid there isn't one unless it has been added in the recent updates.

 

Apple Key-click on a checked box or non-checked box=reverses whatever was there for the entire playlist. Did that make sense?

 

Creating playlists is still the easiest way to go.