cannot delete or overwrite some files

[pawan]

I have a fresh install of ispconfig server 3.0.5 on ubuntu 12.04. I have migrated all the websites from ubuntu 10.04.

Now some of the folders of websites in the /var/www/ or /var/www/clients/clientxx/webxx/ have a padlock symbol on it.

I can neither delete or overwrite any files in these locked folder nor I can copy any files in these folders.

for example there is a file in var/www/example.com or /var/www/clients/clientxx/webxx/web.tar.gz.

now I cannot delete web.tar.gz using sudo. I am able to change the permission of web.tar.gz but not for /var/www/clients/clientxx/webxx

for example

root@server1:/home/pawan# chown -R web13:client2 /var/www/clients/client2/web13
chown: changing ownership of `/var/www/clients/client2/web13': Operation not permitted
root@server1:/home/pawan#

[falko]

ISPConfig uses extended attributes to protect necessary folders from changes, e.g. to prevent people from deleting these folders which would cause the web server to not start anymore.

[pawan]

Thanks Falko,
But the problem I am facing is for some of the folders and not all. And as I have mentioned the problem I am facing in only those folders which is showing the owner as root and I am not able the change the ownership to web and client respectively.
I have around 50 websites and in about 22 website have a lock symbol on it. Snapshot attached