Hmm, Ok. I'd assumed OpenGL would have a fallback for something like this. Is there a simple way (a get call, or something) to retrieve the dimensions of a texture after it's been created?

Edit: Nevermind, just found it. Well, I used [color=#3F0B80][font="Arial"]glGetTexLevelParameteriv[/font] to get the width and height, it returned 1920 and 1200, as it ought to be doing.

Check out glGetTexLevelParameter.

Next step then should be to look into how you're drawing it.

Not for the first time, I feel remarkably stupid, it seems I may have had the wrong texture bound during the render. However I'm entirely sure that was the full extent of the problem; binding another texture temporarily and then binding the render texture again seemed to mess up the sizes, but I may have missed something else there.

Edit: Right, fixed it now. I had some dodgy texture handling going on, some old code that I had forgotten to replace. Thank you to those who tried to help, and apologies for wasting your time =P