I upgraded from Redhat 9 (RH9) to Fedora Core 3 (FC3) and encountered the following problems: 1. I had to uninstalle imap and install dovecot by hand and edit the /etc/dovecot.conf "default_mail_env = mbox=%h/Mail/:INBOX=/var/spool/mail/%u" because it assumes if the directory is called Mail/ it's mailir and if it's mail/ it's mbox. 2. Firefox failed to start, silently. I removed /usr/lib/mozilla/plugins/* and restarted and it worked.