Are you using the QT client? If so, you need to update to version 1.6! You can get 1.6 here It's ABSOLUTELY necessary. Backup your wallet.dat file before updating, just in case. After you update, open it up again and see if it starts syncing. If it doesn't, you need to go to the Dogecoin directory (never used Mac, but Google says it should be located at - /Users/”your mac name”/Library/Application Support/Dogecoin), delete the "blocks" and "chainstate" folders (don't delete anything else), then open the client and it should sync. It will have to start from the beginning, which sucks, but it's probably your best bet.