someday i just messing around w ith my wpmu and suddenly my tinymce wysiwyg didn’t worked it just show blank, after some search on the internet i found this solustion
– go to your wp-config.php in my case it is located on /home/public_html/wp-config.php then after <?php add this
define( ‘CONCATENATE_SCRIPTS’, false );
if it is still now working you can try another solution :
1) Simply download 2.8.6 manually (from the wordpress homepage) and unzip and navigate to the js/tinymce folder in my case /home/public_html/wp-includes/js/tinymce
2) Copy the ENTIRE tinymce folder and paste it over the tinymce folder in my existing website.
3) Upload the new tinymce folder and its contents to your ftp.
4)Refresh cache and page and my wysiwyg