ok guys i have a 15in i5 that i put a travelstar 7500 500gb hdd in. since doing this the hd makes some strange sounds and im not sure if this is normal. basically the hd makes a couple soft clicking noises and then spins up slightly. after about 10-20 seconds it makes the same clicks but spins down and is nearly silent for about 5-10 seconds. this continues to repeat itself throughout use. i didnt notice this when it was sitting in its external housing during power up or data transfer. i also dont noice it when reading or writing...everything seems to work great when its actually in use. anyone have any ideas/suggestions? this is very annoying!