The information I provided isn't "bogus." There are a limited number of things that could create that situation he presented. Based on his EXIF data, some of those could be ruled out. Specifically, aperture size, shutter speed, and battery power.
That leaves his ISO settings. Correct?
ISO100 is fairly fast for indoor picture with little to no ambient light. If you think back to the days of film, a higher ISO would always have been recommended.
Disputing this fact seems rather pointless to me. However, if you believe me to be in error, please feel free to post some shots taken in a windowless room with your camera at 1/60 and F4... using ISO100.... and a 420 EX with no FEC.
To get back on point, I think this problem would easily be solved by bumping up your ISO to a more suitable option (such as ISO200).
And SublimeJoe.... you CANNOT compare the picture taken with your 430 and the one taken with no flash because you used different shutter speeds (1/60 vs 1/15 - big difference!)
Put on your 430 and try using ISO400 and post those results. I think this problem will magically resolve itself.