I have a 787 and a couple days ago the Navionics South 2010 came in so I took it out and plugged it into the 787. The first time I turned it on the contour lines for Hillsdale lake (hi-def lake) showed up just fine for a few minutes then disappeared. So I thought I must need to upgrade the software on the 787, since I have never upgraded it. I took the boat out tonight and everything ran slow on the 787, kind of like when I have too many programs open on my computer. It only happens when I have the map and the sonar split screen on. And the contour lines still disappear, I think the reason they disappear might be because the chip is a mini SD plugged into a SD converter, just too many connections and the mini must be slipping out a little. I can turn the unit off pull the mini out a little and push it back in and turn the 787 back on and it will work a while, but later it will loose the contour lines again. Has anyone had problems like these or is it just me? 
I think the version I upgraded to is something like 4.770
