Toshiba laptop now with win 10 download on it. have had critical error twice but resolved both times. switched laptop on today and critical error came on screen, used powersuite to resolve it and when it came up to the end of its run, a box came up for a restart so I did. upon starting up the only thing on screen now is what appears to be vertical line flashing up at quite a high speed.this problem is something new for me, so if anybody has any idea how to resolve I would be most gratefull.