Got this recently used, and have an older 14" Apple monitor (the one with the built-in speakers on the bottom) plugged into it. It will start the boot process, then quits just before you can actually see the extensions which are loading march across the screen, and makes no further startup progress. If I try starting with extensions off, it boots fine. It came with 8.0 and was doing this, so I completely reinitialized the hard drive and installed 8.5...still exactly the same thing. What is the final check these go through before actually loading extensions? And why would all be ok with extensions off? I have tried creating a startup set with only the minimal extensions needed to boot, still won't complete the startup process. No other software is installed...can't get that far!