Unable to preview or download files

I previously was able to access all files in the box folders to which I have access (word, excel, pdf).  However this past week I have been able to access PDF files and word documents.  The preview does not load and gives the message: "We’re sorry, the preview didn’t load. This document may be protected."  So I then try to download the file, but it does not download.

The team sharing the folders insists nothing has changed with my access rights.

What is going on? Please help!