Thanks for your help -- it worked, but now I have a new, possibly related problem.
When you go to my site,
http://allalias.com/forums/ , it says in purple "
You are currently being served by the
NEW SERVER" but when you go to
http://forums.allalias.com/ you get "You are currently being served by the
OLD SERVER" -- it seems the subdomain is going to my old server.
To make sure this wasn't a mistake I uploaded a text file "old.txt" to my old server, which you can see here:
http://forums.allalias.com/old.txt . However, it doesn't show up here, and you get a 404:
http://allalias.com/forums/old.txt
ETA: Now, even more weird, going to
http://www.allalias.com gives you the old server. Dah!
How can I fix this?
Thanks!