IMac 2009 MacOS 10.6.8, 4GB. I am trying to get the computer going for a friend so that Yosemite can be installed. The system takes extremely long time to load. I reinstalled the system but it is still taking long (over 5 min) in the blue screen before the desktop appears. The system permissions and disk repair were done successfully several times. Also all tests of TechTool Deluxe passed. In the startup disk preference , I can not choose the volume to restart…msg appears… (The bless tool was unable to set the current boot disk). I tried to boot from an external hard drive… with same results. How do I get this blessed tool to bless? (The computer does restart with the option key) Once it comes up, the computer seems to be operating okay. I also realize that 4GB of Ram is the very minimum and it should be upgraded but it should work the way it is. Even though it passed all the test that I can do, I suspect hard drive issues… or could it be a logic board problem? I am stumped… could use some welcomed ideas!