I don't know what happened but after I've updated ISPConfig a co-domain is linked to two domains. On the second domain I can't change or delete the co-domain, i get the message that I don't have the right permissions to change this co-domain. How can I delete this co-domain ?
Please delete the co-domain on the first website, then wait 2 minutes and empty the recycle bin. It should disappera now in both websites. Then create the co-domain on the first website again.
This might happen when there is a small corruption in the database. All co-domains are linked by records in the isp_dep table to their websites. In this case there seemed to be 2 links for the same co-domain. I dont think that you will have to do anything to solve it as your databse should work now again.