Editing Ariel post breaks BBCode

If one manually edits the first post in a topic generated by Ariel, the BBCode for the tags breaks like so:

[url=http://www.phpbb.com/styles/db/index.php?i=browse&mode=group:component⊂=boardstyle]Board Style[/url]

The freaky symbol before =boardstyle in the example should be &sub. For some reason when editing manually, &sub is parsed to freaky symbol.