I have a zoostorm that came with windows 8.1. then I upgraded to windows 10. after a year it started playing up so using the supplied disc I reformatted back to windows 8.1. Once running it works perfectly but to get it running I have to go through turning it off pressing the cd player auto eject put in the format disc and start pressing F7, 8&11,12 repeatedly. This sometimes works or I press the Delete button repeatedly , this also sometimes works If it dosent I repeat the process till it does Sometimes takes 30 minutes Any ideas Please