There is a issue I found where if a vampire is disabled in your cell, then enabled in your cell a Get Line Of Sight command in the vampires SMELL YOU script will CTD.

I have never seen this CTD happen before I started using this new Halloween/Vampire quest mod. I am working now to try to understand why the this new quest mod is CTD with my mod.
But if you do not see this CTD issue with vampires actors that are "suddenly" enabled in you cell you should be fine for now.

If you are a modder please look here:

http://www.gamesas.com/index.php?/topic/1143002-getlos-command-ctd-issue/page__view__findpost__p__16705058

solved the CTD issues.

I just added this to the Vampire can see you script:

DistanceToPlayer <= ( ( 6000 + vampire.getav sneak ) - ( player.getav invisibility + player.getav Chameleon ) * 600 )

So now magic as well as distance will help to prevent the vamp from seeing you with their super vamp vision!
There is more to this formula but this is a big part of it.

Best Ever REV
4.2

READY FOR DOWNLOAD!

if you have already installed this mod then
YOU MUST DO A "CLEAN" INSTALL OR YOU WILL GET A CTD!
So sell your holly water first!

Get is here:

http://www.invision.tesalliance.org/forums/index.php?/files/file/668-duke-patricks-nosferatu-class-vampires/

Thanks Duke, grabbing it right now!