I'm replacing textures in Texplorer and most have gone in perfectly but some are showing up dark on one side. It must be the games shadows or lighting since turning can eliminate the darkness temporarily. I don't know why this is happening to some textures and not others. I am saving them in the proper formats according to the Wiki.
Are you sure your normalmaps are in the correct format? That looks like a format issue to me. Don't use the Photoshop NVidia DDS plugin to save to V8U8, it causes similar display issues with normals. Use kfreon 's ImageEngine, SDK's DirectX Texture tool or AMDs Compressonator to convert to V8U8.