After an email back and forth with both the DropBox-Team-support and the startup, I got my account back in the exact same state as it was in, when my account got revoked. I still had all of the startups stuff but it no longer synced. As I was many GB over the limit of my free DropBox-account I deleted all the files belonging to the startup (which of course is the right thing to do).
I'm glad this is getting some attention, because it is clearly not working very well as it is right now. Hopefully DropBox will make the user experience better.