I have that same problem ,
I tired everything. I just tried to switch both CRT sreen conectors my 17" aoc who works fine one the DVI converted to analog port. and my 15" old Lite-on on the analog VGA port.
so when I tried the Lite on on the DVI port (with converter) the power went on , but I didn't get anny picture , ass soon as Xwindows is started.
Maybe this is the problem why twinvieuw wont work either. Could you check if your 15 " works, if you put it alone.