ViewSonic VA2012w wierd display

[drunkenmaster]

I have updated the latest drivers for my 7800GT and my dispay settings for the monitor are 1680x1050 which have worked previously fine uptil now.
The strange thing is that my actual desktop does not fit onto the screen. Either the start menu with icons dissapear (left) or the clock and system tray icons disappear (right)and when i move the mouse to the left or right edge of the screen the desktop moves to revealing the correct side.
I cannot use the monitors Manual Image Adjust or Auto Image Adjust, as these options are greayed out and cannot select them.
Please help as the only thing I can think of is to rollback the drivers, but then new games such as Bioshock (which I am desperate to play!!)require the newer drivers.
Many thanks