Just curious where you're downloading them from... Do you have a cloud server, or are you pulling them down from a work server. Your work should provide instructions on what applications to use to view and/or edit the files.

I've never seen what you're describing, so I can't provide an easy solution. But would guess when you download Office, you shouldn't have any more issues. That is if your office version is current with your work files. (I.e. as new, if not newer. You may have issues if you load an older version of excel to read these files, but you can always save them in an older format.)