If you checked and all is fine, it maybe a be a temporary bug, it happens from time to time.
The 100% rate could be that it was only one crawl, hence 100% error rate (1 of 1), just wait for the next crawl.
Anyway, in the meantime, check your domain with a DNS checker, you can use www.dnsstuff.com, www.intodns.com or dnscheck.pingdom.com/ to make sure everything is working correctly or to see if there's anything you need to take to your hosting provider.