Suggest you download a boot-able diagnostic. (check Alienware support page to see if they have one, otherwise google Ultimate Boot CD)
Since it went thru bios your HW could be fine. Suggest you poer down, then power up hitting the key used to enter BIOS (f10?? no clue on alienware) then see if the system is stable while you look at a few BIOS screens. If system is not stable in BIOS then it's not a windows driver or other software problem. IF system is stable then software is suspect. (There may be diagnostics accessible from the BIOS too).
I've seen a similar problem when a PC detects what it thinks is a bootable CD, DVD or USB device.. but the device doesn't actually have a boot image. Suggest you remove any media attached to your laptop or use the boot image menu key during power on (nearly always f12) during startup to make sure you are booting your internal hard drive.