Wrong redirect / logout after form post

[reneejtjuh]

Yesterday I installed Prestashop, but I'm not so lucky I guess, and have some problems.

First of all it starts with the login page. When I login with the correct user information, Prestashop redirects me to the same login page over and over again.
I fixed this with some modifications from this thread: http://www.prestashop.com/forums/viewthread/71366/#345774
After I could log in, although I'm not sure if this is a desirable fix.

Next I tried to do some configurations. I tried creating the .htaccess. After pressing the submit, I get logged out. Also when I try to do some other configurations Prestashop keeps logging me out.
For example if I try to change the shops language from Dutch to English and press the submit button, I get redirected to the login page. The urls looks like: http://www.website.com/website.com/administration/login.php?redirect=index.php?tab=......... although it should be http://www.website.com/administration/etc....

There is probably something wrong with cookies, sessions, but I can't figure out what the problem is.

Somebody with these same problems?