We are using 365 at our school without the desktop version of MS Office. If there were existing excel files on the system prior to taking off the old Office version (2007) when we try to open them from 365 after uploading them, they just download. Upon further review if we try to open them from the desktop they seem to have been associated with Microsoft Media Player (even though they have a *.xls or *.xlsx extension). This makes these files inaccessible even from 365.
Any help would be much appreciated.