I have a mesh with a texture from a rendertarget. On my PC it works perfect, but on my xbox the texture gets darker the further away I pull the camera, until it's only a black surface.
I tried different shaders, but it doesn't change anything.
Im pretty sure it have something to do with the rendertarget, if I use a normally loaded texture there is no darkness.

How is it being used?

From your description, are you using a rendertarget to create a texture and setting it on the mesh each frame? Because that's the only way I can see the camera position possibly affecting the contents of the texture. If so then it might be something else?

In other words, if you're creating the texture from a rendertarget once, then it must be how you draw the object. Make sure you're not setting any fog renderstates, or any fog effects for that matter.

An easy way to check is to draw the contents of the rendertarget on top of the screen, and see if it changes as you move around. This will tell us if it's actually an issue with the rendertarget or something else.

Also, can you post your drawing and rendertarget-using code?

Im only drawing the texture once and I have no fog (that would show in the PC too). Except from being dark its very noisy too, like a bad TV reception.

My girlfriend is blocking the TV, I will add a link to the project instead (in a moment)
PC
http://www.hlidskjalf.sverok.net/signaler/BraindeadUtkast.zip
XBOX
http://www.hlidskjalf.sverok.net/signaler/Braindead.ccgame

After looking around, my guess is that the problem does occur from using multiple rendertargets, the xbox doesn't somehow like that, see here:
http://msdn.microsoft.com/en-us/library/bb203938%28XNAGameStudio.10%29.aspx
The problem is that MSDN is out of date and the examples in it does no longer work.

I guess this will take a few hours of googleing before I know whats going on.. I'll be back!

EDIT
Here is an image showing the black noise compared to the PC version.
http://www.hlidskjalf.sverok.net/signaler/xbox_noise.jpg

Yes the Xbox doesn't play nice with MRT... The best solution would be to rewrite it so you don't need MRT. I doubt that's very helpful though. :)

The problem is, I want to do a random texture so Im using thousands of images that I render to a target. Rendering these each frame is impossible, there is just to many small objects. I guess that I could try making one massive rendertarget that all the tiles share, but I dont have high hopes.

What makes me confused is that it does somehow work, and if I zoom in really close the problem is not there at all, so why can it half-work??