I have some strange behaviour on Windows XP boxes (the same code on Linux doesn''t have the same behaviour). Ruby 1.8.2 and Rails 0.14.2. I have a single inheritance table nodes with a base class Node (acts_as_tree) and some subclasses such as PageNode and FolderNode. If I render the tree in an iframe in a set of iframes it doesn''t work, if I render it stand alone it works (there are three iframes with different url:s for each, nothing strange). The error is really bizarre. On some of the nodes ruby complains that "children is not a method". But it doesn''t complain on all nodes and which one differs a lot from request to request. If I do: rescue puts node.class.name puts node.kind_of? FolderNode ... it prints, for example, FolderNode on the first line and then says false on the second line (including the times when the first puts actually print FolderNode). Very strange. It feels like there is some problems with script loading. Each node subclass has it''s own file but they are all found in the /app/model dir. Is this a problem? Any ideas? Am I vague? /Marcus Various different errors gotten when just hitting refresh in the browser: - undefined method `display_name'' for #<PageNodeType:0x36acc38> - undefined method `children'' for #<PageNode:0x3761988> - undefined method `children'' for #<FolderNode:0x37ac5e0> - uninitialized constant Node (the line indicates error where FolderNode class is defined) - The single-table inheritance mechanism failed to locate the subclass: ''PageNodeType''. This error is raised because the column ''type'' is reserved for storing the class in case of inheritance. Please rename this column if you didn''t intend it to be used for storing the inheritance class or overwrite NodeType.inheritance_column to use another column for that information. - uninitialized constant FolderNode - The single-table inheritance mechanism failed to locate the subclass: ''FolderNodeType''. This error is raised because the column ''type'' is reserved for storing the class in case of inheritance. Please rename this column if you didn''t intend it to be used for storing the inheritance class or overwrite NodeType.inheritance_column to use another column for that information.