Dell 2209WA screen fault

[Phadrea]

I have had this monitor for 5 years but of late the bottom left corner of the screen seems to pick up an impression of the music software sequencer I was running previously. There is still a faint trace of it again today but can only be seen on certain shades like light grey and sometimes white.

Can anyone help what this might be and more importantly how to stop it?

[Valo]

https://www.google.ie/search?q=2209WA&oq=2209WA&aqs=chrome..69i57j69i60j69i61&sourceid=chrome&es_sm=122&ie=UTF-8#q=2209WA+screen+burn