Displays Recurring Monitor Problem - Dell 2007WFP

I've had a Dell 2007WFP for a few years. If you look at the photos you'll see what looks like a dirty mark along the top of the screen, as if something is leaking down.

This is very noticable on a photo or a game but when a solid colour is displayed it doesn't show at all.

I managed to catch it on the very last day of my warranty and had it replaced. The new monitor was fine for a few days then the exact same problem happened again!

I haven't contacted Dell as I'm out of warranty but I would really like to know what is causing this.

Also, something possibly worth noting, on both displays the screen is mostly slightly warm to the touch all over except at the top where the "bleeding" is where it is noticably a lot hotter.



Closeup:

 

This has stumped me. Anyone else have a go?

 

You can ask the Dell service/repair; they will give you an exact answer.

 

My dell was out of warrenty and they still replaced it gratis, so yeah give dell a shot

 

Saw that once before. De-lamination of the polarising layer or something. I can't remember exactly now. Maybe worth a Google?