After finally restoring Leopard onto my MBP Late 2007 edition, I am trying to upgrade it to Snow Leopard. At first, there were no problems. I updated Leopard to 10.5.8 and then proceeded to install SL. Everything went smoothly: I looked at the install time and it said something like 37 minutes remaining. I left the room and came back to see the home screen. Turns out the installer quit during the install. Now, every time I put in the Snow Leopard disc into the optical bay, it spins for 30 seconds and then ejects it. Trying to troubleshoot this, I put the disc into my Mac Pro. Works fine there. My last idea was to create an image of SL and put it on one of my flash drives. After doing that, my MBP recognizes SL and begins the install but it begins it partially installed (I would say something like 33%) and says there is 33 minutes remaining. After a short while (the progress bar move somewhat prior), it says that it cannot install SL and tells me to restart the MBP. Any ideas what to do? I have a feeling that, somewhere in the HDD, is the partial install from the disc that failed. Any other ideas? Like I said earlier, I had a good amount of problems trying to reinstall Leopard onto the machine after reformatting the drive. Any help is appreciated. Edit: After looking under Macintosh HD, I see an additional folder called "Mac OS X Install Data". Could this be the problem? It looks to mainly be printer drivers inside of it and is 3.54GB. Edit #2: After deleting this folder, I am starting from the beginning of the install but, again, I get "Install Failed". I used this disc once to update this MBP but, after reformatting the drive, I can no longer access it from this MBP.