I received this error after adding a content pane to a panel page. It really didn’t make much sense, looked like it might be related to a malformed machine name.
https://drupal.org/node/1055766 – here is some info about the error in general.
what i did to fix it was remove the last Views Content Pane that I had added and saved. The error disappeared.
I opened the View itself and saved that without making any changes and was able to readd the pane to the page and viola! no more error. Very odd….