my site is: http://doubanjiang.com/ (writte in chinese), it's running a copy of wordpress 2.0.1,
the follow story has happend 3 times!
someday I set theme to "Blix 0.9.1", works fine.
but the day after that, the theme change to "WordPress Default 1.5" automatically.
i've changed my wordpress password, but this strange thing didn't stop.
and there not such a problem when i running wordpress 2.0.0