I keep running into this problem on my Toshiba a305 laptop. I have run Ubuntu once before on the laptop with absolutely no problems. But all of a sudden about every other time I boot up the computer goes from the grub menu to just a black screen and the Caps Lock light is flashing. Then I have to hold down the power button to restart and try again. This sometimes happens 3 times in a row before it will actually boot up. I also ran memtest and found 0 errors. I am thinking that it could possibly be my hard drive failing. I just wanted to know if anyone else had any ideas on the issue. I have also reinstalled windows 7 twice and my current version of Ubuntu twice, therefore it can't be an operating system problem.