No idea why things just happen in XP. You can do 50 installs to the same computer,
same hardware and all will be fine. Do 1 more and poof, you have problems. It's been
with computers since day one and was given the name "Bit Rot" which basically means
no one has any idea why it happnes.
My current theory is Gamma Rays hitting the hard drive and causing bit changes
in the registry. Black hole gravitational warping is another possability :-)