I have had trouble with openid lately too - I think that the standards have changed - or that there are new methods that the latecomers to the openID party are using. There is a new version of the openidphp library that we use, but it contains significant changes, so I couldn't figure out how to make it work. I was hoping the original plugin author was going to work on it, but I haven't seen anything yet. When I use your checker tool, it tells me that I don't support checkAuth, which sounds like a different error than what you are getting. I only use openid (so far) at LiveJournal, and the friend who I used to use it for has switched to another service.