If you use HumminbirdPC, this is what you might see with either corrupt or phantom waypoints. (Click on any image to enlarge) 

Bad Routes on Current Version HumminbirdPCBadRoutes_HBPC

Bad or Duplicate Waypoints on Older Version of Humminbird PC  BadWaypointsHBPC

Invalid information if you are using Waypiont Management BadWaypointMgmt  

Reset the waypoint and route buffers in the Interlink and the unit.  This procedure is a little more complex but still easy to perform.  Use the Interlink Status screen to check the values.  Note the number of extra waypoints or routes. Usually they are shown under Locked but not always. Add up the additional waypoints and routes that are shown to be used in the steps that follow.  

 

1.     Save your NAV Data to a SD card for backup.  If possible load them on another unit or a PC using Humminbird PC.  Verify that you have your data securely backed up before proceeding.

 2.    Go to the Interlink menu and select Stop Participating on both Units InterlinkStopParticipating 

3.    Go to the NAV tab on the unit showing the phantom NAV data and select Delete All Nav Data (or Format Nav Directories in version 6.250 or higher).  This will clear the unit of all Waypoints, Routes and Tracks

DeleteAllNavData  ConfirmDelAllNavData  ConfirmDelAllNavDataY_N

4.    Go to a GPS/Nav screen and manually mark the number of phantom waypoints and routes you counted.  You will have to move the cursor each time you mark a waypoint to mark the next one.

5.    Go to the NAV tab, select Waypoints, select Share, select Lock All by pressing the right arrow on the 4-way cursor

NavMenuWaypoints  SelectWaypointsToShare

6.    Exit back to the waypoint tab and you should confirm saved changes.  Select Share once more, this time select Share All.  

ConfirmWaypointsSharing NavMenuWaypoints SelectWaypointsToShareShareAllWaypoints  ShareAllWaypointsConfirm 

7.    Exit out of Waypoints and return to the NAV tab. 

8.    Under the NAV tab select Delete All Nav Data.  This will clear the unit's buffers.

DeleteAllNavData  ConfirmDelAllNavData  ConfirmDelAllNavDataY_N

9.    Go to the ACC tab and select Start Participating under the Interlink menu. 

StartParticipating

10.    When asked how you want to participate, select Keep Data on this unit.  Answer the confirmation message yes.  The Interlink sync message will now appear.  When this is complete the Interlink and unit buffers will be cleared. InterlinkSync

11.    Then tell the unit to Share all waypoints

12.    Now go to the second unit and repeat steps 9, 10, 11