Okay, hopefully someone can help. I am lost. I have 2 "mid 2010" macbook pros. The hard drive crashed in one of them. I purchased a new 500GB drive (replacing the original 250 GB). I formatted the 500GB drive with MAC OS ext journaled file system. I installed the drive into the macbook pro. Turned on the computer, inserted my Snow Leopard disc, shortly after, kernel panic "You need to restart your computer.......". I restarted, same issue. I tried restarting holding down the option key and the only thing that shows up is the installer dvd, not the hard drive. If I click on the installed dvd, a minute goes by and then the kernel panic again. I removed the 500GB drive and installed it in my other macbook pro and I was able to install snow leopard without any issue. I removed the drive and put it back into the laptop that started all this headache and bam....kernel panic. The weird part is, if I take the drive out of my working macbook pro and install it into the macbook I am having the issue with, it boots up with no problems. What could be causing this? PLEASE HELP!!