grey box keeps appearing on pc screen

[queen 1954]

i keep getting a grey box appearing in the center of my screen.its says contrast at the top then a red oblong strip and then 100 under the strip.sometimes it comes and goes and sometimes its there all the time its only been happening for the past few days.i cant click on it as the cursor goes behind it.hope someone can help as its driving me mad thanks in advance.

[interele]

Home and Gardening might not be the best place for this question, however,

Most monitors have buttons on the front to adjust the picture. When you press them the monitor will put a small picture on the screen. It's done by the monitor so the computer knows nothing about it, hence the mouse goes underneath it,

Firstly, Is something resting against them, a book or the keyboard perhaps. Secondly have you got some gunk in it so that the buttons stick. (Note do not take your monitor to bits - there are dangerous voltages inside - a wipe with a just damp cloth while the monitor is off and unplugged might help)

Lastly, the buttons on the monitor may be faulty. Basically with the price of monitors verses the cost of an engineer means that it's either live with it or buy a new monitor

Hope that was helpful

M