That's fascinating, Aneagle!
I never use the Windows picture viewer, but I tried it on one of those PNGs and indeed it does mutilate the image terribly. I also tried it on another (non YM) PNG, with same result.
I normally use IrfanView (also free) which is fine - so I'd guess the PNGs from YM are really quite ok, but the Windows viewer is at fault.
HBKid, I hope that explains your smearing, and you'll be happy now !??
30min Googling turned up THIS, which has links etc covering the problem, I guess.
I suggest either upgrade to XP SP2, and/or use IrfanView or one of those that Aneagle suggested, rather than the built-in XP viewer.