URL Rewrite breaks Gallery2

I’ve just set up Gallery2 from the panel, and added a few hundred photos into several albums. Then I turned the URL Rewrite plug in on, and everything broke. I had to turn it off using the technique here (http://wiki.dreamhost.com/Gallery).

I have not tried to modify my .htaccess in any way. I just want to enable “URL Rewrite”, but it doesn’t seem to work.

Any suggestions?