WOOHOO!!
I installed Windows 2000 Professional SP3 and with terrible nervousness click Start > Shut Down.
There you go! Stand By!
There is no more a tab called APM in Power Options either. Also in Device Manager now it says:
Advanced Configuration and Power Interface (ACPI) PC.
Yada Yada Yada!
Thanks trminatr! my first ever hardware problem which needed a reinstallation. Thanks again, hadn't you gave me that Q article I wouldn't never think reinstalling. I am very grateful.
Now let's see whether same thing happens to Windows XP. Oh yeah hopefully!
P.S: Sephiroth, we have both posted at the same time.
I decided to format C: and install Windows XP again. Thanks again!