1998 Volkswagen Golf Water makes car cut off

My car cuts off in heavy rain or if you drive through a huge puddle. In these situations, I only have 10 seconds to get off of the road, and then it won't start up until it dries off (maybe 15 minutes, maybe a day). This has happened about 5 times in the past 3 years. I have been told it could be the distributor cap, but that did not fix the problem. I have also heard that there is a crack in the lower part of the ignition switch, and that the dealership is the only place to get it fixed. Do you know anything about this? I understand it is a common problem on this particular model vehicle.