Dell monitor

Hello

This is a question where some IT person may be able to help.

I have a Dell computer, and I keep getting a dialog box appearing which states the name of the monitor (E...P) and then has various options, e..g Exit, settings. The problem is that it just appears in front of the work I am doing, but does not respond to either mouse or keyboard.

There is also a padlock which appears, sometimes locked, sometimes unlocked, which similarly does not respond to mouse / keyboard.

Has anyone come across this and can anyone help .... as it's driving me mad!!??

Thank you.

SA