Cannot "View" excel or word attachments in Comcast email

When I click "view" on a .xlsx or .doc attachment in a comcast email, I get a black screen with a message that says "An error occurred converting the document so it cannot be displayed.  Please download the file using the button below".   I am able to view a .pdf file.  

I forwarded the email to an Outlook email address and have no problem viewing the documents, so this is looking like a Comcast issue.  Anyone have a solution?