Hard Disk making strange sound

[Chrono]

a few months ago, i picked up a 250GB WD hard disk to i could use it as a extrernal hard drive.
after using it for a while, i decided to put in in my computer, and make it a secondary drive utill i upgrade my comp, so it would become a extrenal drive again.

the problem is that it worked fine as an extrenal drive, but as an internal one, whenever i start up my compter, it makes a loud (compared to any other sound my computer makes) grinding kind of sound... althou this fades by the time i get to the windows login screen.

im just worried if its doing damage to the drive, what could be causing it, and if i could fix it... thx

 

[Biohazard_2.0]

What is the RPM on the HD, if you dont know post the specs on it

 

[FlashDude]

Do you have it mounted properly? (tight enough and the support bolts aren't to long) Make sure you have the jumpers set to master and slave. after you check the above things, try removing the drive and let it just rest on something in the case and boot it. You can also try checking the drive for error's. Most of the time a noicey hdd is on its last legs.