I just tried going to your website, and it worked in both Google Chrome and Mozilla Firefox, so that's a good start. An error like "IP address could not be found" could be the result of a few different things, but primarily it will be one of three:
1) The DNS isn't setup properly, or is still propagating after a recent change (24-48 hrs) 2) There is an issue connecting with the hosting 3) There is a problem with your internet connection (ISP)
Since it's working right now, I would recommend to clear your cache and cookies and restart your computer, just in case. If it continues, it will likely be something with your internet connection or your hosting that you will need to troubleshoot. Once DNS is set, you shouldn't see any problems until something is changed.