Why does an old laptop say invalid boot disk?AnswerOn my old Toshiba the cause was an empty BIOS battery: after years without power, the BIOS settings had reset, including the harddisk interface mode. Setting that mode back to enhanced IDE made the 2.1GB disk boot again.SourcesFixing an invalid boot disk error on an old laptop (snippet, the answer above is its summary)https://willem.com/en/2016-06-23_building-the-blog-in-style/ (full article)