No longer usable – Forced time.ly-network-Sign Up leads to internal server error

I realized that my calendar-events weren’t updated for a while and wanted to check this in the settings. There i got the message that i have to sign up for a time.ly-network-account to further use and manage the feeds. So when i pressed sign up or even the setting-button (both of them leads to …/wp-admin/edit.php?post_type=ai1ec_event&page=all-in-one-event-calendar-settings) i get an internal 500 server error. i’ve even completly deleted the calendar-plugin and installed it again – same error. I am currently no longer able to use this calendar!