iCal - server is busy or unavailable

I keep getting this message:

The server is busy or unavailable

The server is currently unable to handle the connection due to a temporary overloading or maintenance of the server. If this continues you should contact the server administrator.

You may try to connect to the server again or take the account offline.

Go Offline Try Again

This has been going on for several weeks. I'm on 10.6.8.

Anyone have any solutions? I tried unchecking the calendars on icloud and selecting them again but it didn't work.