Alienware Aurora R4 goes from BIOS to blinking cursor

My brother turns on his Alienware Aurora R4, running Windows 7 (64-bit) and BIOS version A06,  and the BIOS splash screen comes up as usual, the loading bar gets approximately 25% of the way full, then it beeps once and the screen goes black with a flashing cursor (underscore) in the top, left, corner and just sits there.

No recent changes have been made to the machine (hardware or software), and it hasn't had any issues previously; however, he somehow managed to unplug the machine while it was running the night before, and apparently the boot to blinking cursor was the first boot since.

I really have no idea where to go from here in terms of diagnosing the problem, but I have a sneaking suspicion it has an easy fix...

Any help is appreciated, I haven't found many similar problems through google...