Hello. There have been several times my Toshiba laptop (2 yrs old running Windows 8.1) has started up only to show a black back lit screen with a cursor (arrow). It goes no further. Fan is working. Usually it will start back up on if I force the shut down and restart it. One time it didn't start back up for probably 5 different tries. One time it also started up and stopped with a blue screen. I have checked the RAM, powercord/box, and have run a diagnostic test which shows no problems. I have not seen any wavy screens or error codes or anything like that. Any ideas?