Computer Restarts to a blank screen with blinking cursor in upper left corner

I was doing nothing out of the ordinary. My computer is usually on all the time. For some reason, my Outlook wasn't receiving my emails properly, so I restarted the computer and it came up with a blank screen and the blinking cursor. I have a Dimensions 4700. I tried to hit the F2 or the F12 or any F key for that matter, and it doesn't repond to anything. I have restarted it numerous times now, called tech support ($39 for what?) and have read numerous posts, which seem to have the same problem, but the people indicated upgrades or Ram issues, and I haven't done anything accept  shop and browse online, check email.

 

Obviously, I am kind of stressed right now so if anybody can help that would be great.