I noticed if im working in photoshop and i save the psd first and then save it as a dds or png that max won't update. Im not sure if your saving it liek this but i try and save out the file i need first THEN save my psd.
I've always had this problem from what I can remember, the "solution" was to keep the material editor open, but minimized, and to be within the bitmap slot that gets updated. For example if you have a wall that uses material #1, and material #1 has a texture called "wall.tga" in it's diffuse slot, then you'll need to be in…