Apple's iWeb, combined with MobileMe, is an easy and effective method of publishing your personal Web site. Some users, however, encounter issues when attempting to publish their newly created or updated site using MobileMe.
When faced with publishing issues, there are a few places to look, most of which are fairly simple ways to solve the problem without having to be too technical.
The first thing to consider when facing publishing errors in iWeb is your Internet connection. Be sure you are connected to a network and that the network is connected to an ISP. Open System Preferences > Network to check on the status of your connections.
Next, be sure you are logged in to your MobileMe account. Open System Preferences > MobileMe. If you see a sign in form, enter your username and password to log in to your account.
Sometimes, though, users may find that they are logged into their MobileMe account properly and iWeb still returns a publishing error saying that they must first log in to their MobileMe account. Apple Support Discussions user Jesse Melchior1 had this issue:
I just tried to publish some new things on my iWeb site, and I received an error message that I needed to sign into Mobile Me to publish, although I was already signed into Mobile Me. I attempted to check the Mobile Me preference pane, but I repeatedly got errors saying Mobile Me could not access my account info at this time. I logged out of Mobile Me and tried to sign back in hoping this would correct the problem. Now it won't log me back in at all...it keeps saying my username or password may be incorrect, even though I know it is not. I have double and triple checked it, as well as signing into Mobile Me on Safari with the same username & password...which works fine.
In this situation, save your work in iWeb and close it. Open System Preferences > MobileMe and click "Sign Out..." to log out of your MobileMe account. Click the Apple logo in the menu bar and choose Log Out (Shift + Command + Q).
Log back in to your user account. Open System Preferences > MobileMe and sign in with a false username and password. You will get an error message that the account name is incorrect. Enter your correct MobileMe username and password after clearing the error message.
Open iWeb and attempt to publish your site again. This should allow everything to publish correctly. Of course, there are some other issues that could be happening to prevent your site from publishing. Most commonly would be maintenance or downtime occurrences on the MobileMe servers. To check on the status of MobileMe services, log in to your account on me.com.