Frontend Loop & no Backend Login

Hi @ all,

I have a problem by using WordPress as www.
I tried to install wordpress using the Adress http://www.tauchgeraffel.de
tauchgeraffel.de (without www.) is working!

After sucessful installation without www. I tried to change to www.
After that, the Backend logged me out, and I cannot log in again. there’s also a loop at the Frontend. When I remove www. in database everything is working.

Can anybody help me?

Kind Regards,
Kai