Never mind, I just deleted the filesystem and created it again using Gparted under Linux and now the card works again. This is very strange because the card still worked fine in my Laptop. Somehow the update process must have damaged the filesystem which the Wiz then couldn't handle anymore while my Laptop could.
edit: Yeah, could also be a rare bug. Anyway: If someone runs into it, just reformat your card.
edit: Yeah, could also be a rare bug. Anyway: If someone runs into it, just reformat your card.