Apparently, you've tried to open a dmg file and the machine's caught in a loop. Open the Console app in /Applications/Utilities/, show all logs, click on All messages, do a string match for repair_packages, which is used by Disk Utility to verify or repair permissions on installed packages, and see what it's trying verify or repair.
This thread has been closed by the system or the community team.
You may vote for any posts you find helpful, or search the Community for additional answers.
Repair Packages
Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.