This is just a guess, but hopefully it will get you looking in the right direction. I know that build.prop file is somtimes modified to tell different programs what your screen resolution is. This should be set by the person making the build, and I would guess that they have it set correctly, but you could always do some searching on this on XDA Developers to see what I mean. build.prop - xda-developers
However, if you tweak this too much, or make the wrong tweaks, you'll hose your device. Don't just go mucking with it without good reason...