Fatal error: Call to undefined function _field_file_load() in /usr/home/sites/mysite.org/sites/all/modules/mediafield/a

I don't know what happened here, but it stopped an entire page from displaying at all after I had posted a test node with a single mp3 audio file on board ... I could edit and post the node o.k., but as soon as I tried to look at the page it lived on, I got this message ... I've had to shut down the mediafield and getid3 modules until I get some guidance ... any help appreciated ...