Wrong URL's to posts and pages after multisite migration

Hi guys!

I migrated my wordpress blog to multisite yesterday. Everything went great and it is working properly, except for the fact, that the urls leading to pages and posts are wrong. They use four w’s (http://wwww.sample.com) instead of three.

Before the migration I did not remove the www from the siteurl but I’ve made sure, that the site address and the WordPress address are the same. I simply did not have the possibility to change the siteurl via the admin panel because these fields were disabled, so I thought it might work.

The linkings are only wrong linking to pages, posts, etc. but not in the admin panel itself. New posts also have the wrong url. All the links for editing and so on are correctly with three w’s (www.sample.com).

I already tried changing the urls in the config.php or via the database, but nothing helps and I can not find an url with “wwww” anywhere…
Does anyone know this problem and how to solve it? I would be more than glad to get a solution as soon as possible.

Thank you in advance!