What could be causing this? White box,please click for pic.

I have a geforce 6600gt agp. Not overclocked and does not go above 70 on full load. I have tried many different drivers and installed a new 550 watt power supply. This is the only game this happens to.

Is the box static or dynamic?

What i mean is, does the box appear like that from every persective, or does it change shape as you move around it (it looks like a 3D box).

If it's dynamic it might be a model glitch or a missinf model file. Otherwise, perhaps it's your monitor, something to do with the refresh rate?

The beginning of a 'reboot' crash.

Check if your CPU or RAM are trying to go supernova.

Restart your game, as there is probably a corrupted file in there. It should do a "Repair Archive" at the beginning, and you should be good to go.

The box is 3d it does not change. All temps for cpu, ram and the such stay in spec. The pc nor the game crashes. I have only noticed this when in towns not during quests or mission. Thank you for all the input.

I got this once too... after exiting and restarting the game, it did a "repair archive", just as Esprit said, and it fixed it. You just have a corrupted file for a character image.