Are you certain this isn't related to a plugin that you have installed or possibly some other special string that has been added to your wiki syntax (perhaps for an entity, smiley or acronym)?
Have you tried this at the playground of any other DokuWiki installation, e.g. http://wiki.splitbrain.org/wiki:playground
. I tried it on the sidebar wiki and didn't see anything out of the ordinary ... http://wiki.jalakai.co.uk/wiki:playground