Have you tried rebooting?
If the program really wont start (and it did before), there has to be a reason related to some change you made on your Mac.
Thanks for the help. Via your suggestion and deleting some preference files we have been able to get it back up.
I notice this is your 47,838th post. That must be some sort of record?
I've racked up more posts than anyone on the InDesign forum, but I've also been around longer than most users here. I'm not sure I'm even in the top 5 these days, though, for the forums overall. There are some very prolific (and helpful) folks over in Dreamweaver and Illustrator, for example.