Sorry, but that did not solve the problem
I made a backup first of my entire site (including dbase) and then copied the two files you mentioned (of which I noticed the timestamps are from December 2nd 2013, so that looked promising).
But when I clicked the save and close, nothing happend and my site was screwed up again: no calender.
Besides that, the cancel button was not present in the toolbar, so I assume that something is not yet completely correct with the latest version....
Regards,
Sjaak