Remco, you may not have been put into the sandbox yet. The way it works is that a new site gets indexed first by Google, then 2-3 weeks later Google places the sandbox filter on the competitive keywords you are trying to rank for. Then the waiting period to emerge from the sandbox. If the keywords aren’t deemed that competitive by Google, then you will continue to rank for those. Our site which was sandboxed back in January has always ranked well for a dozen or so non-competitive terms, some by luck and others by design.