MMC keeps crash after joining the server group.

On one of the Storefront server open command prompt in elevated mode and execute following commands to remove virtual directory 'VirtualDir' if exists

1. Move to instsrv directory
   cd %systemroot%\system32\inetsrv

2. Get a list of virtual directory entries
   appcmd list app

3. This will come up with a list of apps like so
   APP "Default Web Site/" (applicationPool:DefaultAppPool)

4. Remove Virtual Directory called VirtualDir
   appcmd delete app /app.name:"Default Web Site"/VirtualDir/auth

Problem Cause

Some old sites remain in IIS. StoreFront has no right to delete it.