Laptop loading problem!?

my toshiba laptop when it loads after its been turned off it shows "toshiba innovations" which is normal but after that when you normally go to the black screen where it says load normally load in safe mode or load in safe moad with networking in grey, it just shows one little grey line at the top left hand corner of the screen and it wont load anything else! what does this mean? or what could it be caused from? thanks for the help!