I store all of my iCal calendars on my home web server in a Subversion repository. This worked flawlessly from when I last wrote about it until about two weeks ago when I changed the password that Apache uses for Subversion authentication. When that happened, iCal was unable to connect automatically to the server. Once I entered my new password, it worked until I restarted iCal, but then I had to enter my new password again. It was acting like it still had the old password saved and was using the old one instead of the new one. I ignored this for a few days, but then it really started irritating me.
The solution was pretty simple: open up the Keychain tool and delete everything that even vaguely looks like it could be used for authenticating against the web server in question. I ended up deleting almost a dozen entries, presumably dating back to when I first started using iCal years ago. It took me three or four tries to find them all, but once they were all gone I was able to connect to everything.
This brings up a bug in Keychain Access.app, though–it’s really lousy at deleting things. In many cases, deleting items seems to delete them from the keychain database but still leaves it visible in searches in the keychain tool. I had to stop and restart Keychain Access repeatedly to make sure that everything was gone.