String offset cast, Array to string conversion, Illegal string offset, Invalid argument. When using Media

Hi,

Not sure if this is the right place but a variety of problems are occurring when I use the media module to link remotely to various media.
The major problem is that the media is not inserted on the first attempt and after pressing submit in the pop up form the entire underlying webpage is rendered within the popup box (see attached image). Also the following php warnings and notices are displayed.

So my first attempt to link a youtube video produced this warning:
Warning: Invalid argument supplied for foreach() in element_children() (line 6370 of /includes/common.inc).

Linking to a sound stream produced:
Warning: Illegal string offset '#printed' in drupal_render() (line 5892 of /includes/common.inc).
and
Notice: Array to string conversion in DrupalDefaultEntityController->cacheGet() (line 369 of /srv/http/vhosts/bigblacklist/includes/entity.inc)

Linking to an image produced:
String offset cast occurred in _field_invoke_multiple() (line 322 of /modules/field/field.attach.inc)

any ideas?