I just noticed a strange bug in Ask Apache. When I use the WP search for a 'normal word' there is no problem, as soon as the word has an accent somewhere, I get a "You don't have permission to access /bookreviews/ on this server."
It seems to happen when the ?= string contains symbols such as dum%C3%A9zil (for Dumézil). When I turn off Ask Apache, the problem goes away.