I'm using a GXM30 XM antenna with my GPS378. System has always been reliable. I use it for weather radar and XM radio in addition to the normal GPS nav stuff. On a very wet two day ride the XM stopped working. I plug and unplugged. It seemed to work for a while. I cycled power it worked for a shorter while. Eventually - all the while riding in a downpour - it didn't respond at all. This was a real bummer becuase I was using it to see the heavy storm cells. The second day of the ride in the pm it cleared up. After 3 hours of nice sunnny riding the unit fires up again. 1) I thought these were waterproof. 2) Anybody had this problem? 3) Hints on a cure?