Did you choose a theme and are stuck with a stupid error in tiki version 1.6, 1.6.1 or 1.7 ?
There isn't a fix yet, but there is a trick :
should reset your style in emergency.
hope for a real fix soon...
Note : the recover method only works when you do it just after the bad style change (while in a valid authenticated session). The other way is by a direct mysql query :
update tiki_user_preferences set value='moreneat.css' where value='brokenstyle.css';