Ubuntu: upgrade to Dapper crashed in the middle

[Man-wai CHANG]

> A few minutes worth of research will save a lot of grief.

The official how-to forgot to mention the need to comment out
non-ubuntu repositories in /etc/apt/sources.list. :P

My 2nd dist-upgrade attempt worked. But I still have a few
problems in the init process. One is sendmail.

-- 
   .~.    http://changmw.homeip.net
  / v \  May the Force and Farce be with you! Linux 2.6.16.18
/( _ )\  (Ubuntu 6.06)  13:01:07 up 19 min 0 users
   ^ ^    load average: 12.55 8.63 5.03
news://news.3home.net news://news.hkpcug.org news://news.newsgroup.com.hk