i brought my macbook for an hard disk upgrade. after it gets the new hard drive, it doesn't see the old hard drive which i intend to use it as my external drive. the strange is that when i run window (i'm using 2 OSs on my mac), the macbook sees the external hard drive. when i tested the hard drive with other macs and PCs, they can see it as well. only the my macbook on OSX can't see it! many people suggest many times the cause is from a power shortage. but my box (which covers the externa drive) even has 2 USB jacks which one of them ...as u know..feeding electricity to the drive. not sure whether this is the cause.... the machanic who upgrade the hard disk for me was a PC guy who seemed to know little abour Mac. he did a data tranfer from my old to new drive, saying he used a 'cloning software'. my new drive seems to get all data but the old drive lost almost all (it supposed to retain all data as a backup). there was also many problems which caused me to reinstall the OS. so..pls help how to make my macbook to see its old harddrive again for which i can use it as a backup. thank you.