[Mediawiki-l] Help with logging in/user preferences/"short" URL

[ddv hiding]

I decided to go with the '"short" URL option using redirection in my
Apache server.  Following the FAQ instructions I added the appropriate
lines to httpd.conf:

  AcceptPathInfo On

  Alias /wiki "/var/www/html/pubwiki/index.php"
  Alias /index.php "/var/www/html/pubwiki/index.php"

I modified my LocalSettings.php to refer to my "alias" as the
ArticlePath, and I modified the script paths:

  # The *real* directory
  $wgScriptPath       = "/pubwiki";
  $wgScript           = "$wgScriptPath/index.php";
  $wgRedirectScript   = "$wgScriptPath/redirect.php";

  # The *pseudo* path seen in the URL
  $wgArticlePath      = "/wiki/$1";

While the URL seems to work and my pages load properly (after clearing
the cache), when someone logs in they cannot access their
"preferences" page.  It continues to see them as "not logged in".  In
fact, the upper right corner of the page reports them as anonymous (ip
address, "please log in", etc.) even though they can click on 'edit'
and it records their ID.

What am I missing in all this?  Why isn't this working?