The Advanced Usage → Running Defraggler from a USB drive page reads:
You can install Defraggler to and run it from a USB drive.
Why would you use this? If you want to take Defraggler with you to defrag other computers, this can come in very handy. For example, if your work PC doesn't allow you to install new software, you can simply run Defraggler from a USB drive. Or, if you want to help out a friend by defragging his PC, you can bring over Defraggler without having to install anything on his computer.
Problem here is that I can open Defraggler but cannot run neither its Analyze nor its Defrag feature. I get this error message:
Process aborted due to: Access denied.
How can I overcome this lack of administrative rights, if there is a way?