Change Resolution > Screen Goes Small

[Resolute]

Hi,

 

I've got SL 10.6.4 all work, wireless, sound etc.

The problem is, if I up my resolution to anything higher than 800*600, the screen goes to 1440*900 but the resolution stays the same, so I'm left with a small 800*600 box in the centre of the screen. I'm pulling my hair out at this as I've been trying to figure it out for hours.

 

Any ideas? Thanks