: : What makes you think that it's the hard drive?

: : Make sure that your hard drive is in a position that allows air flow around it.

: : Fit a case fan.

: : Buy a hard drive cooler fan.

: : Are you sure it's not the chip overheating? Remove the cover. When it freezes turn off and quickly touch the edge of the chip/heat sink. Grip the case as you do this so that you are not charged with static. If you can fry eggs on the chip or the heat sink then you need to replace the fan. Use a heavy duty fan. If your fan is an old one then it's possible that the bearings are on the way out or it is getting full of dust and slowing down.