Nodebuilder Failing

When I was making a new map for my project, I decided to call it a night, I tried to save the map but it gave me an error message saying:
I have been up for the past two hours trying to fix it such as redoing the sectors, removing some things, and even restarting my computer. I don't know what is going on. When I build the nodes manually it works and I can still test the level and edit it in 3D Mode but when I save my progress I get this message. I think it might be this sector I'm made that is causing me problems but I don't know...
This does not happen on anyother map for this particular project I am working on.

Is that your only sector? That error always pops up if I have just one.

Did you build that inside the big red square?

Lippa said:

Is that your only sector? That error always pops up if I have just one.

Click to expand...

This also happens when I have multiple sectors on the map. I'm just showing you the sector that I think that is causing the problem.

NeroTheArmadillo said:

Did you build that inside the big red square?

Click to expand...

What is this big red square you speak of?