Registration window locked up; can't be killed

Registration window popped up when I rebooted; I clicked on ‘re-register home version’ and the window locked up. I could not close or kill the window.

I finally figured out how to turn off self-protection in the Avast options, but this was really annoying. Must the nag dialog be protected, esp. if it tends to lock up?? Not exactly a strong motivator to pay for professional ed.

This message shouldn’t be blocked…
How many times did you install/uninstall avast? The first trial period is 60 days.
It’s NOT a nag window to force buying the Professional version.