Maybe the computer is trying to say something... "Li.. Li.... Linux.....", sorry about that, couldn't help myself.
I reckon it's either a RAM or HDD fault.
The easiest thing would be another stick of RAM or a different RAM slot. Maybe even dust out your PC a bit (if its dusty)
If that don't work, try going to http://www.seagate.com/support/seatools/
and downloading the seatools program, (if you have another PC) and put that onto a disk and see if there's anything wrong with the HDD.
Hope that helps!