Why do all the added input sources disappear on reboot?

Since installing Mountain Lion, every time I do a full reboot (or power down and restart the system), the input source that I added in the System Preferences > Language & Text > Input Sources (in my case, Dvorak, which is the main one I use) gets removed, and the default setting is US Keyboard again. This means that every time I have to go into System Preferences and check Dvorak again to have it reappear in the menu, and then switch to it again.

Somehow the system is not remembering the input sources I've set after rebooting. Thanks to anyone who can help me fix this annoyance.