Hi everyone, I've got a very huge issue that needs your help. I got a Macbook Pro (2010 version). It was working pretty fine all this time but somehow it just became a bit slow compared to when i bought it. Then last week, it just got a bit slower than usual that i decided to restart it. And when i did, it wouldn't go past the grey screen with an apple logo and the spinning wheel (it would get stuck there for hours!!!). I searched the internet for some solutions but none of them could solve my problem. I even had to format my disk, lost all my data that wasn't backed up yet, and still it didn't work!!! I also tried to reinstall the OS but i wouldn't work. One time the installation was successful but when the computer booted, it didn't go past the grey screen. Stuck there again for hours... Then i was told that my hard-disk is dead. So, i went out and got me another disk: a Western Digital 500Gb 5400rpm disk but my Mac can't see it (i.e not visible in Disk Utility). After trying again and again, i decided to change it to Hitachi 500Gb 5400rpm (because the original says HITACHI 160Gb 5400rpm) but the same problem persists. Strangely, if i put back the old hard-disk, the computer can see it!!!! Now again i changed to Seagate 500Gb 5400rpm and it still doesn't work!! Surprisingly, both disks work fine if i connect them to an external enclosure (except for the Hitachi disk which even Windows OS can't recognize: the worst of all!!). Is there a way of fixing this problem? I really don't know what to do.... Whatever ideas or suggestions you have are so welcomed. I REALLY NEED HELP WITH THIS GUYS, PLEASE!