I have installed dual boot wind8.1 with ubuntu 14.04. when I turn on the computer from a complete shut down status, everything is alright and I can access both win 8.1 and ubuntu from grub. but when I restart from win or ubuntu, if I choose win in grub menu, the system crashes without even entering the windows welcome screen! it just stays on a dark messed up page and I have to shutdown the system by keeping the power button. I tried to reinstall ubuntu and also using boot-repair, non worked!