For the Golf with Rain Problem, how does the water get to wherever it causes a problem? Possibilities:
(a) General moisture splashes or condenses and pools up somewhere, causing an electrical short.
(b) A passage allows water to flow directly onto a circuit somewhere that it causes a short. We suspect the drains from the sunroof; however, keeping a plastic bag over the sunroof during a rainstorm is only partially successful at preventing the problem. (If at all.)