I just started a new job, and they have CS5 on their Mac, purchased on Tech Soup some years ago. It hasn't been updated much, so I'm trying to get everything current. Half of the products updated, but the core products -- Photoshop, InDesign, etc. -- are a no-go. It's saying I have an invalid serial, and when it takes me to the help page, it describes what I should do at initial install. But the suite is already installed with a serial already entered. I don't know where to find on the computer what it is (it seems to be lost at the office) or where to change it, if it's incorrect. I assume it was correct, because it's installed, and successfully registered to this account.