I am trying to install CS5 (upgrade from CS3) and I am getting a message stating that my serial number for CS3 is incorrect, this number is the right one from my original box and is the one I installed CS3 to my PC years ago.
Any advice please?
Contact Adobe Support , Check the link for details :-
I agree that you should check the eligibility for an upgrade, but also remember, if you go to Help>About, the S/N that is displayed is truncated for your security. Make sure that you have the full S/N from your original product.
Good luck, and if things fail, and you are qualified, contact Adobe Customer Support (not Technical Support), as they should be able to help you.