Great, monbron.

Monbron, it sounds like you've set your monitor to a higher resolution that it allows. That's not supposed to be possible. It may be due to some screw up in your graphic card driver. You can try to update your driver, or simply lower the resolution. See if you can find some manual or description of your monitor, where you can see what its maximum resolution is.

Thanks Mikael, I checked my Graphic card and it is NVidia GeForce GTX650 Ti and the setting is called 'native' which I assume is the usual one allocated, I do have a very old monitor 'Acer IL1912' which is about 10 years old but seems to work perfectly (until now) but I have no info on this monitor, I could try a search and see what it throws up.