PROBLEM Upgrading 3.3-14 > 3.3.15 BIG Problem

[SoHo22]

Hi there,
after upgrading from 3.3.14 to 3.3.15 the page loads without stylesheets or images and navigation links don´t work.

I guess the problem is the path which isn´t set as a relative one. For example <?php get_theme_url(); ?> gives full URL back instead of the relative path /themename/...
Same with all images and internal links.

Would you please help to fix this problem?

Thank you and best regards,
Sabine