V1.2.1 Broken link to CSS

Once in a while wordpress generates a scrambled css link (it adds many false folders to the link e.g. /smilies/ /images/ ….) so that the css file cannot be found.
Here is a sample of the code that I get:

<style type="text/css" media="screen">

@import url( http://mzeecedric.de/blog.v3b/wp-login.php?redirect_to=/
blog.v3b/wp-admin/wp-style/wp-images/smilies/
wp-images/smilies/wp-images/smilies/wp-style/
cactus/wp-style/cactus/wp-style/cactus/
wp-images/wp-images/smilies/wp-images/
smilies/wp-images/smilies/wp-content/
wp-images/smilies/wp-images/smilies/
wp-images/smilies/wp-images/smilies/
wp-style/listenlouder/style.css );
</style>

It also forgets the login, so that I have to login again to the adminarea.
As soon as I login the page is displayed correctly, at least for a while.
This happens with Firefox and IE 6.0.
Any one seen sth. similar? Ideas on what to do about? I would appreciate your suggestions. Thanx.