Check the UV map editor to see if the textures are still listed in the datablock ID field. If they are, shift-click on them to unlink them, even if they show up red already. Then save and reload.
Also, if you added multiple textures to one material, or shared one material with multiple objects, you get cross-referencing that confuses Blender, so go through all your materials for all your objects and make sure that the problem texture isn’t still assigned to another object.
Another thing to note… When you join objects that are textured, and they share the same material, the assignment of the materials gets messed up and the textures can get switched. I did this last night and found that one material that was being shared by several objects got duplicated when I joined everything, and the textures got messed up. I didn’t notice until I rendered, at which point the unwanted texture showed up where the original one was. I had to go through the steps I suggested above, and things cleared up.