[Plugin: NextGEN Gallery] Problem with wordpress 2.6

Hi guys,
I’ve a problem with NextGen Gallery and WordPress 2.6 over https://www.zerogradinord.net.
Today afternoon I’ve downloaded and installed the new WordPress (upgrade from 2.5 to 2.6). Before I used NextGen Gallery and work very good.
After that, I put the new NextGen Gallery and I’ve a problemn with the slideshow widget and with the visualization of the image over the past post. Actually, I can see an empty space with an red X but the name of the pictures is the right one. If you click over the pictures, you can open the right image.
Instead, if you go in the page dedicated to the photogallery, there is no problem and you can look the pictures.
Another problem is in the text editor: when you click over the plugin button, you received the message: internal server error.
Can you help me? I use the web site for work: is a sailing magazine on the web!
Thanks.