When I have done updates in one Fallout 3 mod (and this mod only), with GECK (updated), I save by click on save button (top of the left), I have this advertise :

Assertion

"Assert


File c:\Fallout3\Plateforms\Common\Code\Fallout
Shared\Pathfinding\NavMesh.ccp

Line: 1680


|Abandonner| |Recommencer| |Ignorer|



More that, the path c:\_Fallout3\Platforms\Common\Code\Fallout Shared\Pathfinding\NavMesh.ccp does not exist...

What does it mean ?

GECK contains bugs and flaws. Overall I don't think it means much other than sometimes it will crash and you will lose unsaved data. Be sure to save often and be prepared to restart GECK from time to time. And if you use Win7/Vista, run GECK in administrator mode. Just remember that if you edit the navmesh, your plugin needs to be converted into an .esm. The AI doesn't read the navmesh very well in .esp's and your NPC's will have a hard time with pathfinding...