Dell 2200MP & VGA cable - Laptop outputs but projector can't find source

Perhaps someone can help, I have some very strange behavior that I can't fix.

For some time, I have been using my Dell Inspiron E1505 laptop to play movies which I project up onto my Dell 2200MP DLP projector.  I have been using a RGB monitor cable to connect my laptop to the projector.

Recently, the projector no longer can find the signal from the laptop.  If I plug it in through the S-video port on the laptop, it can "find" the signal and display it.   Here are the pertinent details:

1) I've confirmed the laptop is outputting video correctly through its output by using my desktop LCD monitor.

2) Using the same setup I've confirmed that all the output video is set to be 600x800 resolution.

3) Using the RGB to component adaptor cables included with the projector, I hooked up my Xbox 360 to the projector and it ran just fine.  (*Note this means it was passing directly through the main VGA cable I use to connect my computer... so its not a cable problem.)

So, my computer is outputting correctly, the cable works, but the projector refuses to "find" the RGB source.  The blue screen comes up fine, I can even get the white searching screens if I tell it to not automatically search...

Anyone know what I might be doing wrong?  The only thing that's changed lately is that I recently used the S-video connection to watch TV through the projector, I used the component adaptors to play Xbox on the projector, but I don't think I've changed much (if anything) on the computer settings (well, not at first, I've now done things trying to fix the issue.)

Anyone have any ideas for a projector that's willing to find a component source over a RGB connection but is no longer willing to find a pure RGB source from the computer?