I appreciate your reply, but luckily it started working again. I'm not quite sure what the problem was.
Whenever I would plug it in while it was having this trouble, the computer would get extremely hot, indicating that the power cord was not the problem. But the solution to the problem seemed to be keeping the computer plugged in for a long period of time.
I think that the computer attempted to restart while installing Windows Updates and that caused some fatal error.
Thanks for you help.