Garmin 496 suddenly advised "Lost Satellite Reception", and all data fields cleared and the map froze. The first time occurred just as I turned to run parallel with Gatwick zone's Northern edge, near the M25. After about 3 minutes the Garmin fired up again until just South of Guildford, when it popped again. It resumed after about 2 minutes, but popped yet again with about 8 miles to run to Portsmouth. On the return route, the next day (14 Jun 09), (London Westabout), it went twice, once just North of Popham and most seriously, abeam Bourn, when it went AWOL for about 8 minutes. Background info: i. It displayed throughout, but without information, so it doesn't appear to be a power issue. ii. It's powered from the aircraft supply. iii. It has the Garmin remote antenna, (about the size & shape of a hotel soap bar), mounted in the roof structure of my SkyRanger, so I would hope it has a fair chance of 'seeing' satellites. iv. After the last failure, I switched the unit off then on again to reboot it. It booted normally, but did not locate satellites, until some time later, of its own accord. Post-flight, the unit correctly reports only 2 flights, ie one outbound & one return, with correct endurances, so it was 'thinking' correctly throughout, even when the monkey rebooted it. It worked as advertised after each event and appears fully serviceable as I type.