If characters in your journal or User Info appear as ? rather than the proper symbol, or if you have ever used special symbols in your journal entries or user bio (such as accented letters, pound signs, or Microsoft Word "SmartQuotes"), you need to set your default encoding. You will not be able to edit your entries until you do so.
To do this, first visit your Personal Info settings (http://www.livejournal.com/editinfo.bml). Scroll down to the bottom and choose your default text encoding.
If you visit your Personal Info settings, there is, in fact, no setting for "default text encoding." Instead, there is the option to auto-convert old entries, and to translate your email notifications. No default text encoding.
I am not 100% certain how one fixes the character problem, or if it's even a problem anymore. Thoughts?