Yes, this was a javascript problem. I couldn't figure it out, because I did have javascript enabled globally, but AFTER I had installed the extension. By then it was too late. The trick is to DISABLE Adblock Plus, then enable javascript, then re-enable Adblock Plus. If javascript is not enabled when Adblock Plus starts (or is enabled), then the configuration page (and probably more) won't work.
I will keep testing things. I have always run with javascript disabled globally. I literally can not start Opera with javascript enabled (I keep over a hundred tabs open, and all of those scripts trying to run will crash Opera before it even gets started).
I have been using Peter Lowe's adserver list (
http://pgl.yoyo.org/adservers/serverlis ... =plaintext ), which has worked reasonably well in the past. Can you compare the effectiveness to Adblock Plus? Will that filter file interfere with, duplicate, or supplement Adblock Plus?
Thanks for the reply.