I'm having a few issues with my iMac running 10.7.2. Software update doesn't work. It says, "checking for new software" the bar loads up to like 30% and hangs up there. It never goes anywhere. There are also several items in System Preferences that don't work, such as iCloud and Security & Privacy. The application doesn't respond when clicking on those items and I have to force quit system preferences. I've tried running these items in safe boot and that didn't work. In recovery mode, I repaired the disk and permissions. What can be done?