I have changed to a new computer and when trying to download books to ADE it sends error message Error: E_LIC_ALREADY_FULFILLED_BY_ANOTHER_USER.. I did NOT change my adobe ID; so how can I fix this?

I have even gone back to my old computer and also getting same message when i try to move the e book file download from download to ADE.  I have unauthorized  and re authorized ADE but it makes NO difference. Checked with library and they say it is not there problem!