Any suggestions on what is causing this and how to fix it?
Thanks.

[regaining space - attachment deleted by admin]I suspect this is not a monitor but a display CARD problem.
While Salmon Trout may be POINTING in the right direction tell us some more about what we/you are dealing with here. What is this monitor attached to? What if anything were you doing that was coincident to this PHENOMENON 1st occurring? Let us begin there for starters. truenorthThe monitor is connected to my tower via a cable.
The problem first occured when I switched to full screen whilst watching a DVD, since then it has been permanently like this.
My computer is a dell inspiron 530 intel core 2 duo.If its not a onboard video card pull it and reseat it.

If it's on-board video, then try a video card.I doubt that doing the following will do much to resolve your issue other than confirming that it is NOT the monitor. Take your monitor and connect it to another computer. If the situation is normal then the issue is not the monitor. What possibly could change your problem on the computer where the issue is occurring is if you were able to go to your "display" properties for you monitor and change the RESOLUTION parameters it might get you out of the situation you are in. However how you are going to be able to do that when you cannot properly see the display is problematic. You have as yet to tell us whether you video is from an on-board (integrated) card or is a standalone one. Depending on your use and needs video cards can be quite inexpensive (unless you need advanced technology for game playing or high end graphics) so installing a standalone graphics card WOULD more than likely get you up and running again. truenorth