Hello, I am having a problem with my 2011 iMac updating through the app store. I have had Apple engineers look at the problem and they are not much help. The problem is it will not load major software updates. Right now it cannot load iMovie or digital camera raw updates. It starts to load, reboots and craps out saying software could not be installed. The best the engineers can do is to blame it on third party software without being able too identify which software. They tell me to format, install fresh copy of sw and start reinstalling my apps one by one. I can be there for a year doing this. The idea is insane to me. Any ideas? Thanks much.