Over the past few days I have been having difficulty with my internal hard drive. It has been having problems booting up properly; oftentimes it would get stuck on the gray screen and stall there. I was able to save my files and move them to an external hard drive, and I then have tried erasing the drive (zeroing out the data once) and reinstalling OS X Tiger or Leopard but each time the installation hangs, on both possible installations. I have used Disk Utility to verify the hard drive multiple times throughout this process, and there have been no repairs needed. So I decided to install OSX Tiger on an external firewire hard drive and see if my system would work with that. And it works fine with the external hard drive. After getting a stable OS for my computer on the external, I used a 7 pass erase on the internal hard drive, ran disk utility to repair the disk and it was ok, also ran techtool deluxe (including a surface scan), and then attempted a new installation of os x tiger (original installation discs I have). The installation froze again. Any clues as to why the installation keeps stalling? Is it a hard drive issue? Or is there some other issue I should be trying to isolate?