Deleting closed question fails with error "CSRF verification failed"

edit

I can't do it. I can delete them before they're closed by someone else. But the link to delete is still there.

Also, adding a comment on a closed question, instead of being impossible, yields

Forbidden (403)
CSRF verification failed. Request aborted.
More information is available with DEBUG=True.

Maybe that should be a different question, but it just happened to me.