Normal map half working
( here is some guesswork )
if your normal map has an UnpackMin setting of zero, then it will only half work.
you can see this if you use only one point light. ( or a moving light )
lightmass can cover this up pretty good.
so when you import you should use Compression: TC_Normalmap. ( in import window )
then it will setup UnpackMin to -1 for you and the normal map will fully work.
( in texture-properties )
if you change UnpackMin from 0 to -1 manualy there is a problem. ( feb 2012 version 9505 )
it seems it will not update existing materials until you change the compression.
( so if you change to TC_Normalmap first and then UnpackMin to -1, it will still only half work )
also notice that a correctly setup normal map looks darker when you see it in the material editor.
That's not an issue, you just need to make sure you use normal map compression setting when you import your normal maps. That's always been the case.
the issue is materials not being updated. guess i picked a bad title.