Computer Systems : Internal hard disk drive not found

I got this error while booting up my Dell Latitude. The screen said that the system could not find the internal hard disk drive. I was in shock. I tried googling up the issue but to no avail. I even jacked out the system RAMs and cleaned its connectors. I also removed the battery and put it back after few minutes.

After these failed approaches, I entered the BIOS setup to see if the BIOS is actually reading the hard disk or not. If BIOS can't read it then its time to buy new hard disk. With lots of combinations and permutations, I finally hit the nail's head.

I solved the problem in two simple steps:-
Goto the BIOS setup page. This page may look different based on the Dell laptop model.
Step 1 :-
In the Boot Sequence, which is inside the General Settings, move the Internal HDD to the top. This will ensure that the system will first look up into the internal HDD for boot programs. By default, the floppy disk(diskette) drive is set to highest priority.

Although this is not a major problem, but setting internal hdd as highest priority will not have any side effects, as the laptops these days lack the floppy disk drives, which are set to the highest priority in default conditions.

Step 2:-
Next goto the SATA Operation settings, which could be in System Configuration or the Device Info depending upon the laptop model. Set this to ATA.

Why does this problem occur?
Due to improper shutdowns or deletion of files in the windows folder, the BIOS settings would have modified. As the SATA operation setting, that defines the operation of hard disk, is set to some other than ATA, the system can't read the hard disk.

Notes:-
1)This problem was faced in Windows XP and thus could/couldn't work on other Operating systems.
2)The solution worked on Dell Latitude and Inspiron laptops. For other models, you need to verify.