by shannah » Mon Dec 20, 2010 11:44 am
Your AddType directive seems to cause .html pages to be parsed by the PHP parser. First of all, directing your webserver to treat all .html files as PHP files may cause extra load or even open security holes (although I can't think of a likely scenario for the latter off the top of my head).
Second, if your server is set with short_open_tags on for PHP (i.e. it will accept <? as an abbreviation for the full <?php open tag, then this could cause problems with XHTML files whose first line begin with <?xml ...
I suspect that this is what is happening. FCKEditor likely loads a number of XHTML files via ajax, but your webserver is trying to parse the xml as PHP... which causes a problem.
Solution: Remove the AddType directive.
If you have specific pages with the .html extension that you need to parse with php, change their extension to .php, then use mod_rewrite to rewrite requests for the .html pages to the new locations.