You probably unchecked the "automatically login as" check box in accounts prefs. Before that you were used to restarting the computer and landing at your desktop. Now it's asking for a user and password since auto login is turned off. If it's giving a list of users, try the user(s) and see if...
Thank you for the helpful information. I was adding support for sending pictures from my laptop to my server and was getting this error, only when the script ran by cron of course, which was really annoying. I had to implement the applescript solution, and unfortunately this requires a user to...