Thanks, Ed. I'm going to do some trouble shooting tonight - thinking I may have some interference going on with external antenna routing/placement, but still odd though that it will go hours/many, many flights and be fine (and the software slow down issue that we spoke about).
Lee - would be interested in hearing about your mounting/equipment setup to see if we may have some similar scenario for possible interference issues.
Mike - not absolutely sure, but I believe you can still scroll/zoom when the signal is lost. Not 100% positive as I did not try it during the signal outage.
I am more than backed up with a 430, 496, Skyview, and Wing-X (over kill anyone... :) ) but I would be a bit more unhappy if this was my only navigator. With Walter not finding anything in the log files, I'm going to pursue the interference issue more.