Remove the checkpoints, replace the first one with your genesis block. Did you update your genesis block time, news headline etc. as well before you generated it?
Yes I did update my genesis block time and headline before generating it. So that part should be good.
To do the first thing you said, would my code look like this?
static MapCheckpoints mapCheckpoints =
boost::assign::map_list_of
( 0, uint256("0x81570df7c6cb16af5b46e9889f9d1f50982c6c4b7230a690d3545e6c70a843f7"))
;
(is this correct to put "0" there because it's the first block?)