In either case, the file you are attempting to open should be considered as infected until you have updated your antivirus ...

In either case, the file you are attempting to open should be considered as infected until you have updated your antivirus software to the latest updates available from the vendor.   All major antivirus software manufacturers have created updates to address known compatibility problems with Microsoft Office programs.  They also usually provide a virus signature file that is available for download from the Internet and must be updated regularly to properly scan for all known forms of viruses.