minecraft minecraft window pops up screen goes black and freezes

Ok so i was playing minecraft this afternoon and it started lagging so i lowered my brightness to raise my fps. It did so i lowered it all the way but it lagged again so i closed minecraft and when i logged back in the mojang thing pops up and then goes black. Then a separate window tab pops up at the bottom of my screen and my screen freezes! When i click control alt delete and click cancel or start task manager it closes the windows out. I tried logging in on my dads computer and it works so i dont know if its my pc or what please let me know