Yes, the resistor is what decides the 'compatibility' of the generated VGA sync signals, so changing it could very well fix the problem. The most common resistors used are 320k, 470k, 570k, and 680k.
I would try the 680k first, and then if that doesn't work try the 320k. Also note though that you can actually use any resistor you like between 320k and 680k. (I usually use 470k resistors.)
I finally got around to trying the other resistors and had some unexpected results,
first I tried a 680k and had the same results, then I dropped to a 320k and once again the same results, I tried a couple of resistors in the middle and still had the same results, I would of expected something different. I even removed the resistor completely and had the same result. (I think it is an issue with the evo projector).
one thing that is a little weird is that on first boot the screen brightness would flash from bright to dim rapidly, if I unplug the vga connection and then plug it back in, the monitor would readjust and be fine (well all except the top fifth which would quiver like before.).
I am not sure where to go from here, maybe softmod the box, I have heard it has better vga output still. any opinions or suggestions frosty?