so OP did you ever find a solution to your problem.?!? or if anyone else has i'm having these with windows 10 like title forgive the nerco.
I am using Dell Dimension 2400
Dell monitor E171Fpb
A flashing lock symbol appearing in the center of the screen
continuously, Buttons on the monitor not responding except the
power button, Is this related to OSD settings? If it is,
Is there a way to access menu of the monitor to set the OSD settings? Pl. help!