Ist tatsächlich ein Fehler durch ein aktuelles Windows-Update: https://support.microsoft.com/en-us/help/4480970/windows-7-update-kb...
"Applications that use a Microsoft Jet database with the Microsoft Access 97 file format may fail to open if the database has column names greater than 32 characters. The database will fail to open with the error, “Unrecognized Database Format”."