one more thing you need to cheak is the hard drive itself, the cable to the mother board and the hdd, they have a tendency to losen themselves(how this works, is that electricity moves through and actually causes vibrations, this mostly occurs in slot type cards ex: video cards, but CAN happen with other components, i have never seen this with a HDD, but it could depend on the laptop, most of the laptops that i have oppened up have verry thin small cabling that either snaps on or is pinned down by a small lever or tab, i could see these getting loose, especially over 5 years) what you need to do(if you feel comfertable with it) is open up your laptop, look at the HDD pins, and make sure that none are bent/broken, make sure the slot that it slides into(most laptops work this way) is also intact. then continue on to cheack the cable, for breaks, wear, discoloration(such as a burn or an ARCH(this is where electricity leaps from one wire to another) re-seat it onto the motherboard and to the connector that seats the HDD. after this, you need to prove that the HDD is the point of failure, look through your YELLOW BOOK, and see if you cant find a couple of computer stoors and call them to find out if they carry laptop HDD(prolly a 2.5" 9mm IDE) then place the new HDD in the HDD cady and load it up to see if you get the same results. if you do, try replacing the memory by going to the same store(make sure not to damage ANY of the components and be careful not to leave PHYSICAL scratches so that you can return the components to the computer stoor if need/wanted. if you are still recieveing the same problem, the next step would be to trouble shoot ALL other components possible, test anything you can one at a time, if this fails you really only have two more options: you can take the computer to a repair store, where they will prolly charge you and tell you it cant be fixed(this is a lie, parts can be ordered for laptops, but it may be more money than its worth, laptops are in effect desktops, components are removable, i have replaced several laptop motherboards, video cards, Wi-Fi cards etc. ) as your laptop is older, the parts could be VERY expensive, and i do not believe that this is a route you want to take.

your only other option that i see, is flashing the BIOS, i have seen similar error when the BIOS on the motherboard has gone corrupt(i found this forum because i was researching any possible after effects that this might have caused to the BIOS and was considering replacing it throught the manufacture which is another route, though it is a pain), due to improper voltage, viruses, and hundreds of different possibilities, YES viruses can get in your BIOS, this is not a joke and is EXTREEMLY rare. however viruses are the cause of 5-6% of hardware failure(note that this is not an actual researched figure and cannot be quoted, this is an oppinion).

-Dell XPS Agent

NOTE that all the material above does not reflect DellTM  in any way and is not legally binding to any company connected with the POSTEE of this forum document. all information above was posted in goodwill and was taken from experience and oppinion, nothing contained above was researched or taken from documentation.