Unwanted pop-up from Windows Action Center

[pinot]

I use Windows 7, browsing on Firefox; since 4 or 5 days a pop-up message has lodged itself on my screen saying 'Action Center No current issues detected'. The message box cannot be moved, a right-click on the mouse gives no menu, and opening Action Center gives no option to close it. A shut-down and restart has no effect. The box doesn't even have a close or minimize button. Would be grateful for any suggestions. Also the box overlays any other page I open.

[hallmark]

https://www.techsupportforum.com/forums/f217/disable-action-center-flag-on-system-tray-636985.html

[pinot]

Huge thanks for the link; have cancelled notifications from Action Center without disabling it ( which has solved my present problem), though I may try to restore them to see whether the 'annoying' flag reappears. 

[hallmark]