What happens when you try?
When I try to launch ID, I got the error message: "Error 45 String Object is invalid Line 387, Line 345." I apologize for delayed response. No access to home computer Sunday.
Sounds like you have some sort of startup script installed that is throwing an error.
Problem solved. It helps to use CS5 to open a CS5 document. When you use the right key, the door opens. Lesson: Don't store installation discs of inactive versions with installation discs of current versions.