A client used to have "WordPress PopUp" installed (I am not sure if this is the same as PopUp Pro, however, Wordpress PopUp was not a choice). It has been deactivated and deleted. However, the message to install the Dashboard plugin still remains displayed in the dashboard. "Easily get updates, support, and one-click WPMU DEV plugin/theme installations right from in your dashboard - install the free WPMU DEV Dashboard plugin."
If any MPMU DEV plugin was installed, I would add the dashboard plugin. However, nothing is installed at this point.
I even added the line:
to the config.php file and the message still is displayed.
Any ideas? Thanks!