That is the route I have been taking today. The problem showed up on my home computer on firefox with lots of firefox extensions installed, I am now on another computer I tried opera and a clean install of firefox (with no extensions) and have been unable to repeat the problem.
ok I believe you something else is mucking my code. I just haven’t figured out what it is yet. The problem I have had is when I tried to copy and paste code from youtube to embed a video. I copy the code then paste, the code shows up in the code window of my post. Before I have a chance to click save or publish the code just changes in the window. Its very wierd. The code is there correctly for a few seconds then just changes in front of my eyes with out me clicking anything or pressing any keys.
You tell us wordpress is not doing this then I believe you, it must be something else.
The same thing has been happening to me. I have not installed any plugins or themes, just using a default install. Anyone have any ideas?