Hi.. I have a Compaq A902 17 inch laptop with 2.5 GB ram. I just got a new Western Digital harddisk for my laptop, as before, while installtion of Vista or starting of Vista, the laptop use to sound, "tiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiinnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn......." While installation of Vista, when it happens, LOADING WINDOWS FILES , the sound comes out and sometimes, the laptop wont start even if I switch on. It shows blank, then I have to switch it off forcefully and restart the button. But when booting, it gives this error.. I think, my hard disk was the culprit and now I got a new hard disk, but what i see is that, in this new HDD also, when i started Vista installation, it gave out that sound. Now idea, from where it is coming Please help..