You could have mentioned you ported them as this is in the HL engine discussion section and we continuously have people who don't understand the differences between source and goldsource, posting topics in the wrong sections.
So presumably a image with all source assets [How'd you get self illuminative light textures? Additive render mode?] with nothing tying it to goldsource other then the section the thread was posted in, could actually just be a source thread posted in a goldsource section.
With that aside,
As far as I know, the shadow maps shouldn't be affected by the texture [to the extent of that] and it might be worth upgrading your ZHLT, if i recall correctly version 3 isn't the latest and it might have some hotfixes to help with that type of stuff.