acrobat 9 pro serial number

When attempting to open Acrobat 9 Pro now, I get a message asking me for my serial number. Either that or to open another registered product from CS5. I do that, and nothing happens. I get the same message. I've gone through the serial number locator and put in my serial number, and i get a message that the serial number is incorrect. All of my other programs are working just fine, I simply need Acrobat Pro to work. Can anyone help or point me to a resolution for this?

Thank you.