Not possible to post new events

For some times ist is not possible to post new events. I’m able to write all Informations for the new event but it’s not possible to save or post it.
In this case the page “/wp-admin/post.php” stops at white screen. Preview isn’t also possible. To delete an event from the bin doesn’t work neither.

I tried to manually install the plugin, but this didn’t change anything.

The page I need help with: [log in to see the link]