So I finally got my GMX-200 back today after being sent out to Garmin in late August. The issue was intermittent spontaneous rebooting, nearly always preceded by the ownship "jumping" around on the map, sometimes by hundreds of miles. It happened much more frequently in warm weather than in cold, and that pattern was consistent enough that I suspected a failed internal cooling fan. The avionics shop talked to Garmin today and learned that they had been unable to reproduce the problem, but sent the unit back and charged me their $930 flat rate fee anyway for completely overhauling and recalibrating the unit. On the 30 minute return flight home, the display was rock solid: no jumping at all, not even a hint. I thought the problem was somehow cured by whatever they did. But after landing at home base, the display suddenly went black without warning. After coming back up, the error code displayed was 0x20, the same as every time before. Garmin does NOT warranty their service work, even when it is their recommendation to send a unit in. To have them look at it again would cost me another AMU. Let this be a warning to anyone thinking of sending a Garmin product back to the company for service. Their work is limited in scope, they WILL charge you a pretty penny for it, and you have NO recourse if their service fails to fix the problem. As far as I'm concerned, Garmin can burn in Hell.