Serious display sizing issues!!

I have a 23' and a20' screen connected as one(Not mirrored). Today when I turned on my Mac tower the screen is twice as big as normal. It looks like I have gone to 1/2 the resolution of before, but in system preferences>display the 23' is still on 1920x1200 and the 20' is on 1680x1050.

The size of the desktop is literally twice as big as it is supposed to be.

If i move tho mouse to the bottom of the screen, the screen moves down towards what is the bottom of the desktop(like as if i was scrolling down) and i lose the menu at the top.

Anyone come across this before?

J