ccbit on "[Plugin: Postie] After activation 1.4.40 -> 500 - Internal server error."

When I activate Postie I get a "500 - Internal server error". No other plugins are active. When I delete Postie WordPress works again. Any idea?

Postie-Version: 1.4.40
WordPress-Version: 3.5.1
Theme: Twenty-ten
Server: IIS

http://wordpress.org/extend/plugins/postie/

Update: I tried different versions. The latest which works is 1.4.36.