Level/FOF crashes the game

THIS PROBLEM IS SO ANNOYING!!! Makes me want to PUNCH everyone in the face! Sorry but that problem is so annoying...
Attachment 7070(Yes, I named the level Green Greens from a game of a certain pink puffball.)
Does anyone have an idea on how to fix this?

Apolagieze for my total rage there (no comments) ...

We're going to need more info to help. Could you send us a picture of the fof you think is causing the problem in your wad editor? A possible issue is that the fof has a higher floor height than the ceiling, that always crashes the game. But that's just a guess with no info.