word 2007 issue

[cking]

we have a user that copies text from a PDF file and pastes it to a word document then saves and emails this document to other users. All but one of these users can reopen this file fine without a problem, one user though when they open it it starts at 12 pages long and just automatically starts to self expand (to hundreds of pages in lengh). She is able to open other word documents both emailed and saved fine. He has sent her a new copy on several occasions and it still does it. Any help or suggestions would be greatly appreciated