Corrupted word doc

Hi all,

I have a user that complains whenever she saves a word document (she hit CTRL+s) a lot of the time the document get corrupted. I checked out the documents, half of the data are there but the other half are either blanks and\or have these boxes, some of the font looks like these: ??? ?2?

Is the file corrupted or did she saved it in another format? Is there a way to fix this problem and are there anyway to prevent this from happening again? Thanks!