Hopefully this will help someone. I had the same issue, and I got InDesign to work.
I'm using a MacBook Pro, and when I installed Leopard, I did a basic upgrade, and not a clean install. I deleted the Adobe folder in HD/Library/Application Support/Adobe, then deleted all the CS3 applications in the Applications folder, and I re-installed the entire CS3 suite from a backup copy of the original CS3 DVD (to see if a non-genuine copy would work, as this has come up recently) and InDesign now works for me.
I'm using a MacBook Pro, and when I installed Leopard, I did a basic upgrade, and not a clean install. I deleted the Adobe folder in HD/Library/Application Support/Adobe, then deleted all the CS3 applications in the Applications folder, and I re-installed the entire CS3 suite from a backup copy of the original CS3 DVD (to see if a non-genuine copy would work, as this has come up recently) and InDesign now works for me.