Thanks for the prompt responses, guys.
The answer to Joe's question is yes.
Whooami: I have been muddling around with the permissions. It is hard to tell what they are supposed to be. The server is just a seven year-old powermac running os x 10.4, apache 1.3, MySQL and PHP. It usually works pretty decently, even when I use the dnsalias redirection. Once the screen turns white, I have to move things or change their names to make the whole thing work again.
Also: I think I can now make it switch to other themes, so perhaps this one is just flawed.
I am usually a textpattern user, but the very interesting commentpress made me get involved with this wordpress thing. I must say, it seems a bit rough around the edges compared with TXP. But then, I would probably feel better if it had worked for me.