Laptop dual display crashing

I use my laptop in dual display mode quite a bit. I use the laptop display
as the main screen, the expand the desktop onto a monitor plugged into the
VGA port.

However the other day i put my laptop into standby mode whilst in dual
display mode. Since then whenever i boot up, i get the desktop up for a few
seconds, then the blue screen of death appears...

If i boot it up in VGA mode it works OK, but can only use the laptop
display - and i have to fiddle about with the diaply settings to get a
useable screen resolution. If i boot it up in safe mode it crashes.

Any idea's ?