Black screen then restart is ok

Hi, i'm on windows 8.1 preview, every time i turn my pc for the first time it gives me only a black screen with the cursor on it, and then when i turn it off and on again it boots normally, i reboot and turn off again and it works perfectly until the next day when i try to use it it gives me the black screen again, and i have to turn it off and on for it to work. Very weird problem, does...