I've noticed that on one of my sites where I've tried to use tables in the content block on the page I often get error messages when I try to save the changes. A box appears showing the home page of the site, or at least the top right corner of it because the box is small. If I close the content editing box and then exit page editing I get an access denied flag.

I was able to create the table and put content into it, but when I try to alter the alignments these errors appear. I also had a similar error in another area where I tried to add an image to the content area.

These are using the Featurist template if that matters. I've built out all of the site without incident, except these two recurring problems.