Windows 8 App Cert Kit no longer runs?

I am trying to do the App Cert check on my Metro app, but it won't run anymore! Anybody else having this same issue? I've searches all over the Internet, with not even a single related result.

It ran successfully a few hours ago, but now it just won't run at all. The spinning cursor shows, indicating that it's about to open - but it doesn't.

I've tried restarting my computer, opening/closing visual studio, opening/closing my app. It just doesn't run. I've tried running as Admin, I've even tried running it from its actual location - instead of just using the shortcut icon on the Start screen - but it just won't run.

What to do?

I managed to solve this problem.

Run CMD.exe as an Admin, and enter the following commands:

• cd C:\Program Files\Windows Kits\8.0\App Certification Kit
• appcert.exe reset

CMD should now say:

Successfully reset the testing configuration.

Now, enter:

• appcertui

The Windows App Certification Kit should now appear.