I've read several posts about Thunderbird users who receive PDF attachments as "win.dat" files instead. But I have a very different and specific case, where 3 people are all sharing an office and all receiving the same emails from their clients. Two of these folks are getting the PDF attachments properly, but 1 of them always gets the win.dat attachment. They were all using Thunderbird version 102.15.1 so I decided to upgrade them to 115.3.1, and same issue. Just this one user gets win.dat file instead of PDFs. I even updated just that one to 115.5.1 and nothing changed. I've disabled and re-enabled anti-virus software, I've uninstalled and reinstalled Acrobat. I've also made sure to verify under Files & Attachments that PDFs are associated with Acrobat.

Thoughts?