Getting this error still. It appears to be related to having UpdatePanels on the page. I have an UpdatePanel on the masterpage, but the Editor is outside of the update panel.
How can this be resolved, outside of changing the way the page is design and functions with UpdatePanels, which is not really an option?
I have added <add key="CuteEditorEnableGZip" value="False" /> to the config, but that does not fix this problem.