Yeah, I found this out awhile back from the sideimaging forums from personal experience. The card kept loading up the nav data and then telling me it ran out of space. I couldn't figure out why until I checked all of my waypoints in humminbird pc. I had a couple of bad waypoints with bad dates. Fixed that and everything was a go. I was converting waypoints I made from Google .kml files to .gpx to .hwr ..it messed up somewhere but I found the problem before I lost any hair.