New Python Toolbox will Crash Arc Catalog

Has anyone else experienced this?

- Fire up ArcCatalog or ArcMap
- Create a new Python Toolbox (do not modify anything in the default toolbox)
- Close ArcMap / ArcCatalog
- Start ArcCatalog - it will crash with a send report error box.
- Start ArcMap - it will load just fine

Notes:
- I am using ArcGIS 10.1.1.3143.
- If I copy/paste my custom toolbox code into the .pyt, it works fine from within ArcMap but ArcCatalog continues to crash.