It seems the evernote web clipper which I use quite a lot causes problems with Google chrome and luminis. If you are using this combination and are having problems with fckeditor in targeted announcements spinning tirelessly, use another browser or disable the evernote web clipper. Evernote web clipper in IE seems fine, and the compose window in email is not affected.
The error is as follows:
Uncaught SecurityError: Blocked a frame with origin "http://my.school.edu" from accessing a frame with origin "chrome-extension://pioclpoplcdbaefihamjohnefbikjilc". The frame requesting access has a protocol of "http", the frame being accessed has a protocol of "chrome-extension". Protocols must match.
Doing a search for pioclpoplcdbaefihamjohnefbikjilc reveals it is indeed the evernote web clipper extension.
Just an FYI.