I may know a potential cause. Can I see a copy of these two files:
webassist/ckeditor/ckeditor_php4.php
webassist/ckeditor/ckeditor_php5.php
If it is the problem I've seen before I will be able to spot it in these files. I may need FTP access or screen sharing to debug if I don't see the problem I think it may be in these files.