[rightbyte]

Satelite constellation (position in the sky) is date stamped right? If the internal clock date doesn't match the received the updates may be ignored.

[makomk]

The satellite position updates use essentially the same time format as the rest of GPS, as I understand it. So the problem comes when some GPS receivers try and use the latest information but base their calculations on an erroneous belief it's now 1024 weeks into the past, causing them to fail to find satellites.