Hello. I'm having an issue of big, red diamonds with exclamation marks popping up in Tenpenny Tower, which I believe means I'm missing a texture.

Here is a picture: http://i.imgur.com/ak4qvNG.jpg

Can anyone suggest what I should do? I have several mods installed, mainly Fallout 3: Wanderer Edition, NMC Texture Packs, and RH Ironsights...I've already tried installing/uninstalling NMC Texture Packs and also playing the game with no mods loaded. The problem appears to persist. Would appreciate assistance!

What you have is missing meshes. Something did not install correctly. Since it persists after you have uninstalled your mods, I would guess you need to uninstall and reinstall the game.