I did an upgrade from 0.8 to 1.0.1 and everything works fine except the last image of an album. You can see the thumbnail in the overview, but on the image page the following error occurs instead of the image:
Fatal error: Call to a member function on a non-object in /.../zen/template-functions.php on line 656

Feel free to look at the example galery: http://gisela.nic-id.de/zen/Weihnachten05/DSC00594.JPG

Thank you for any advice.

I had that problem when I uploaded the stylesheet from my old version. So my advice is to edit your .css file or to write a new one.

My problems is that I can't upgrade? How do you upgrade from 0.8 or 0.9 to 1.0.1 ???