need a bit more detail...
are you moving when it happens or does it hapen when you come to a stop after having been moving...
If it happens only WHEN your moving...try cracking the gas cap open as soon as you notice it starting to happen...if this solves the problem...then the gas tank vent hose (below your seat and infront of the rear tire) is likely 'clogging' with water and stopping the flow of gas...try cutting the tube at a hard angle (openining a larger hole in the line) making it harder to block with water...or buying a vented gas cap...
if it happens after you come to a stop...it's most likely a water short...use dilectric grease and hit all of the connectors under the tank...and dont forgett that pesky side stand switch....but I'm betting it's the first one!
