**System Information**
Windows 7, Nvidia Quadro 600
**Blender Version**
Broken: 2.73 hash: 3f57714; 2015-01-30
Worked: 2.73
**Short description of error**
julperado informed me on BlenderArtists about this bug here: http://blenderartists.org/forum/showthread.php?350296-Addon-Animation-Nodes&p=2809155&viewfull=1#post2809155
It seems that this is a more general problem with custom node trees.
**Exact steps for others to reproduce the error**
1. Copy this code in blenders text editor:
```
import bpy
class NodeTree(bpy.types.NodeTree):
bl_idname = "test"
bl_icon = "BBOX"
bl_label = "test"
bpy.utils.register_module(__name__)
```
2. Run the script
3. Switch to a node editor and try to create a node tree of the new type
4. crash
Creating the new tree using python works without problems. There it isn't relevant if you use the low level way over //bpy.data.node_groups.new// or the higher level //bpy.ops.node.new_node_tree//. The problem only happens when you click on the New button in the node editor.
And if you already created a tree with python it crashes when you try to open it. So maybe the problem is more that Blender cannot display custom node trees instead of creating them, but I'm not sure.