I can't load up Dawnguard in the CK. I get a string of error messages and then the CK crashes. No matter how many times I try it, I get the same result. Is there a special technique you have to use to open Dawnguard in the CK?

Add Dawnguard.bsa to SkyrimEditor.ini's [Archive] sResourceArchiveList2.

Thank you. It worked.

SkyrimEditor.ini:

[Archive]
bInvalidateOlderFiles=1
SArchiveList=Skyrim - Textures.bsa, Skyrim - Meshes.bsa, Skyrim - Animations.bsa, Skyrim - Voices.bsa, Skyrim -

Interface.bsa, Skyrim - Misc.bsa, Skyrim - Sounds.bsa, Skyrim - Voicesixtra.bsa, Skyrim - Shaders.bsa, Update.bsa
SInvalidationFile=ArchiveInvalidation.txt
iRetainFilenameOffsetTable=1
iRetainFilenameStringTable=1
iRetainDirectoryStringTable=1
bCheckRuntimeCollisions=0
bUseArchives=1
SResourceArchiveList=Skyrim - Textures.bsa, Skyrim - Meshes.bsa, Skyrim - Animations.bsa, Skyrim - Voices.bsa,

Skyrim - Interface.bsa, Skyrim - Misc.bsa, Skyrim - Sounds.bsa, Skyrim - Voicesixtra.bsa
SResourceArchiveList2=Skyrim - Shaders.bsa, Update.bsa, Dawnguard.bsa