custom aspect ratio missing with Intel graphics HD 3000...

I have had a dual monitor setup running for ages with my main monitor being a viewsonic (specifically Digital Television VX2273 series). I've always set up my main monitor by going into intel graphics and media control panel advanced mode and going to general settings > scaling > and choosing 'custom aspect ratio' and setting both the horizontal and vertical sliders to 50.

However, yesterday I unplugged my second monitor and it shrunk my display on the viewsonic!
now I go into the intel control panel again and it shows there is no more custom aspect ratio option for this monitor, only center image (too small) and scale full screen (too big)


I checked the monitor buttons for a menu on there but all the scaling options are greyed out on there.
I plugged in a second smaller monitor and it scaled fine straight away automatically choosing 'maintain display scaling' in intel but also (infuriatingly) having a custom aspect ratio option available!


Any ideas to get the scaling options back on my viewsonic?

I choose intel & driver support from my start menu and this is what it says:

anybody?