Symptom
After a user authenticates at the Login Window, the progress bar appears as if logging in, but the computer stops responding at the progress bar.
Solution
Use SSH to recover from the unresponsive state. Remote Login must have previously been selected in the Sharing preference pane of the client computer. Follow these steps:
1. Open Terminal (/Applications/Utilities/) at another computer.
2. Type: ssh <client_address>
Note: Replace "<client_address>" with the actual IP address or DNS name of the client computer.
3. Press Return.
4. Complete the authentication dialog, using an administrator account of the target computer. You may or may not see an RSA warning message.
5. Type: sudo killall loginwindow
6. Press Return.
7. Enter the administrator account password when prompted, and press Return.
8. Type: sudo rm ~<shortname>/Library/Preferences/com.apple.desktop.plist
Note: Replace "<shortname>" with the short name of the affected user who selected the custom picture.
9. Press Return.
The user should now be able to login.
The following steps prevent users from accessing the Desktop preference pane and changing their Desktop Picture.
1. Open Workgroup Manager.
2. Choose View > Preferences.
3. Click the Users, Groups, or Computers tab.
4. Be sure a user, group, or computer list is selected.
5. Click the System Preferences icon.
6. For "Manage these settings", select the Always option.
7. Deselect the checkbox for the Display preference pane.
8. Click the Apply Now button.
Note: A user still can manually edit the ~/Library/Preferences/com.apple.desktop.plist file, causing the same issue.
This document will be updated when more information becomes available.
For related information, see technical document 107659, "
Workgroup Manager: How to Allow Use of Unbundled Applications".