here is one important post i have found
When displaying images/files using relative urls and config.baseHref, everytime you switch to wysiwyg mode there is a call made to the images/files using only the relative url and totally ignoring the baseHref. Obviously this fails into a 404 (or some other error code depending on the environnement).
The images/files is still displayed, but there is also this unnecessary 404 call.
Please note also that if you're testing this on local static files (i mean something like C:/some_directories/mypage.html) the call won't show up on Firebug, you will need to run it on a server like wamp.
You can reproduce it easily on the online demo with Firebug :
- go to http://ckeditor.com/demo
- go to source mode
- remove all source and paste only the following :
- clear all firebug console and network panel
- hit the wysiwyg mode
you should see the Google logo, and a 404 showing up in both console et network panels.
located the where the call is made, it's in plugins/htmldataprocessor/plugin.js, in the toHtml function
Hope this will help you!!