Mac – Why can’t I sign into the Mac App Store after updating to 10.6.6

I found a solution. Another forum post describing similar issues suggested deleting /Library/Preferences/SystemConfiguration/NetworkInterfaces.plist. I backed that file up, deleted it, and restarted. I can now log in and out of AppStore, access all of my AppStore purchased apps, and it 'sticks' across shutdowns and restarts.

Process is pretty simple, I'll spell it out for future reference:

1. Open Terminal
2. cd /Library/Preferences/SystemConfiguration
3. cp NetworkInterfaces.plist ~/NetworkInterfaces.plist.bak - Make a hasty backup in your home directory
4. sudo rm NetworkInterfaces.plist delete the original
5. Restart your Mac
6. Open AppStore and try to sign in. It should work.

Apparently this works because the MAC address is used as part of the receipt/authorization process.

1. You can log out from the App Store after you click "Account" at the Quick Links sidebar (inside the "Feature" Tap)
2. You can log out and change the Apple ID inside the OS X settings
3. You need to log in with the Apple ID you bought the apps with
4. You can delete certain apps and keep the files. Like iPhoto keeps its Library inside the Pictures folder in your Home directory
5. You have to buy the Apps again if they cost money if you want to update them with your other Apple ID