Network credentials work with a Windows workstation, but not from a MAC workstation

I recently renamed the username for one of our female users due to her recent marriage. One lingering problem has presented itself. She can use her new credentials when logging on to our network from a Windows workstation, but not from a MAC workstation.
     I have renamed numerous usernames over the years for the same reason, but I have never encountered this particular issue. Her new husband also works at our location and they now share similar usernames due to our naming format. His username is his "last name" and her's is her "new last name" (same as the husband) followed by the first initial of her first name.
     Her husband has the same first initial in his first name and at one time he had an alias username that is now his wife's primary username. I believe accounted for and deleted the husband's old alias in our system, but this is the only thing I can think of that is causing a conflict with her new username when attempting a network authentication from a MAC.
      I've had our techs successfully authenticate from the same MAC workstation she was trying to use to rule out the workstation as a problem. Our domain controllers are Windows Server 2008 R2.

Thanks