When adding or modifying text in Messages.properties, be very careful that you have automatic word-wrap turned off in your text editor! The "key" and its corresponding "value" must always be on the same line within Messages.properties (e.g.) This is NOT a valid entry in Messages.properties:
jsp.community-home.heading1 = This is a really long heading
which actually gets wrapped automatically by my text editor
so that it ends up on three separate lines.