I'm trying to navmesh my interior and exterior. When I click on the Navmesh button, the navmesh bar that's supposed to appear doesn't. I've tried looking around the internet, and tried messing around myself to find a solution. So far, I've had no luck, and can't find a thing on this. Any help is appreciated.

something is wrong with your GECK i whould try unistalling it then reinstalling

I've considered it, but I'm going to wait and see if there's a simple fix for it. This isn't the first time I thought something was wrong with my G.E.C.K. Usually, it's just something to do with the G.E.C.K. having minor conflicts with Windows 8, so I'm going to hold off on that until I'm absolutely sure it's something wrong on my end. Thanks for the suggestion, though.

your welcome there might be a compatibility opiton for win8 in the geck

Try to press other buttons) then try to load some other mod and to press navmesh there... Sometimes helps with other functions.