You see, I've got an IIMorrow NMS2001, and it suddenly stopped working
late last month, also with the "NAV FLAGGED" symptom, just like another
newsgroup poster had recently had. I was hoping that whatever was ailing
Mike's system was identical to mine, perhaps a GPS date code change (or
rollover).

My GPS had been working perfectly (albeit with a year-old database and
much older firmware) until last month. (How old's the firmware? I'm warned
about ARSA's!)

Garmin (who took over IIMorrow support when they bought UPSAT) said that
the issue was probably a corrupt almanac, but after setting the date to 1
Jan 2004 at startup, and feeding the GPS its location, it then could give
navigation info to all the waypoints I tried entering. (The GPS took
a long time when first coming up, probably doing an autolocate just
the same.) 45 minutes later, I should have had a complete almanac
downloaded. A power cycle later, and it was again NAV FLAGGED and unable
to locate.

I'm thinking it isn't the antenna, since it does eventually "see"
satellites and sense position and give accurate nav info to other
waypoints.

Before I take it to the shop, I'm wondering if anyone else has ideas about
the root cause of the problem. (And don't say I'm cheap, 'cause I just put
in a new attitude indicator last week. :-)

-Jack