I get strange text inserted and can't use the Enter key

[ogier]

When I am in insert mode in taskpaper, and I hit the enter key, I don't get a newline. Instead, the string <Plug>TaskPaperNewLine gets inserted at my cursor. This is awkward because it means I can't get more than one line in a taskpaper document (the 'o' mapping also doesn't work).

Do you have any idea why this is happening to me?

[ogier]

Further investigation shows that any command using the special <Plug> binding is failing on my machine. I think it must be a configuration problem, since it hits me on both ArchLinux and CentOS 6.3 machines. If you want to try and recreate the issue, my vimrc is public in ogier/dotfiles.