I created a simple signature and when I insert it manually in a message it works fine. But when I go under Preferences, Accounts, and select it under signatures, I cannot save this setting. An error pops up saying "No such identity: <insert 3 blocks of alnum chars here, about 30 in all> which then quickly disappears. The only way out is to click Cancel or do not save.
This is on WinXP SP2, Zimbra Desktop 0.84 (downloaded today, 6/19/08).