Unknown file in login on proftpd 1.2.0pre10-2potato1

[Poe-Min Oliver Wu <pm5@matilda.fiorile.org>]

Hi,
        I've just found that an anonymous ftp connection
        to my box whould leave a file $FTPROOT/var , whose
        u/gid is ftp/nogroup, the same as proftpd.

        I'm using Debian 2.2 with proftpd 1.2.0pre10-2potato1
        on an i386, and this didn't happen before I do an
        'apt-get upgrade' some time ago.

        And while I was trying to close the daemon I found
        that a '/etc/init.d/proftpd stop' won't work.  I have
        to manually kill the process.

        I had the daemon killed for now.  What should
        I do to make sure that the daemon is safe?

pm5