Why am I getting message saying I'm using maximum allowed computers when I only have 1 computer?

[lorem91447092]

I only have one computer and I'm getting error message saying "Serial number is already in use by the maximum allowed computers".  It's telling me to deactivate one, but I only have one computer!!??

[Test Screen Name · Accepted solution]

Which version of Acrobat? Is this a new purchase of Acrobat, installing for the very first time? Or is it something you are reinstalling, having used it before on the same or a different computer?