Either your graphic cards have been taking some damage or its not entirely plugged in to your screen.,
Ive had the same thing, it worked after Ive restarted my computer.
Though I did notice one big thing:
It only worked if Vampire was the FIRST game I started on my computer after ive restarted it properly. Try that, no other full-screen program and no other game may be started before vampire, that should do it. If not, try the same thing and pull out the network cable and start again.
If that doesn't work, the graphic card has taken too much damage.