I have been trying to reinstall my Adobe Acrobat XI Pro DVD for 2 hours now and I am repeatedly getting the same response ' that I have an invalid Serial Number. This is the same DVD that I installed on my computer last year with the same difficulties that I am having now. Do you want consumers to avoid purchasing your products in the future?
You might want to contact customer service: 800-833-6687
They can usually get installation and serial number issues resolved.