This may be a software or hardware issue.

The first thing to check is your display settings - that they match your monitor's resolution and colour-depth. If those are correct, there may yet be a fault with the display driver software. To resolve any issues on that front, download and install the latest driver from the maker's website.

If the above steps don't return your display's performance to normal, it may indeed be a hardware issue, in which case you'll need a PC Technician to test and, perhaps, replace the video card.

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]