I'm posting this here just in case this has something to do with K2.

I can't get the standard Joomla wrapper module to find the URL I've configured it to display. The page displays with an empty iframe ("file not found"). The URL works from the same computer in the browsers and it works if I install the HTML and related files into the Joomla site (separate directory in htdocs), just not inside the wrapper.

Anybody have any ideas about what could be wrong?

Hello Melanie,

Unfortunately this issue is not related to K2.
You should post it at Joomla! 's forums.