Weird behavior on IE when embedding a flash animation in HTML

That's another one of these issues which you don't fully understand, but which can take up a lot of you time. I had to embed a flash animation into a Drupal page. I copied/pasted the code from static HTML page which worked fine in Firefox and IE, but somehow the same code in the Drupal page would not work on IE6/7. After some investigation, I found out that some of the flash HTML code had been altered. The attribute classid of the object tag was originally:

classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000"

and became

classid="d27cdb6e-ae6d-11cf-96b8-444553540000"

That was enough to make IE choke and display a white textarea in place of the flash animation, while Firefox did not have a problem with it.

Not sure what to blame here: either FCKeditor (using view source) or myself. I did try to reproduce this with FCK, but without any success.