New to Mac. Finally found the link to download the Combo Upgrade. Happy Happy! When trying to install the upgrade... get this message: Install requires 506MB of space. I have 46 GB of space left on my root drive! Why won't the upgrade install? I like this computer... but I'm about ready to return to the evil world of PC's if I can't get this thing to do what I need it to do without spending a fortune on new operating systems, etc. Can anyone tell me what I need to do to load this upgrade?