As discussed here: http://dev.fckeditor.net/ticket/325, fck 2.4.2 had a bug related to the getxhtml function of fckdomtools.js
The bug is said to be fixed, but I can still experience it ! I am using [Mozilla/5.0 (X11; U; Linux i686; fr; rv:1.8.1) Gecko/20061010 Firefox/2.0]
I have verified that the 256 changeset [http://dev.fckeditor.net/changeset/256] was correctly patched, and it is.
The patch proposed by [alfonsoml] works great, event if it is described as a hack.
I Hope developers will soon fix this ! thank you for your support.
bug #325 remains in fck 2.4.3 (getxhtml bug)