We get intermittent "An internal server error occurred. Please try again
later" error pages served by pound, and for the life of me I can't figure
out what is wrong. Here's a sample of what shows up in the pound log:

Oct 16 04:22:12 pound: (b73dfb90) e500 response error read from XXX / POST /
sudoku-lookup.pl HTTP/1.1: Success (0.043 secs)
Oct 16 05:34:16 pound: (b69e7b90) e500 response error read from YYY / GET
/js/game-common.js?20091008.03 HTTP/1.1: Success (0.000 secs)
Oct 16 05:47:22 pound: (b6ebab90) e500 response error read from YYY / GET
/js/common.js?20091008.03 HTTP/1.1: Success (0.001 secs)
Oct 16 10:31:47 pound: (b7bffb90) e500 response error read from XXX / POST /
login.pl HTTP/1.1: Success (0.187 secs)
Oct 16 10:41:38 pound: (b79b6b90) e500 response error read from YYY / GET
/js/common.js?20091008.03 HTTP/1.1: Success (0.000 secs)
Oct 16 12:13:41 pound: (b7628b90) e500 response error read from YYY / GET
/css/main_blue.css?20091008.03 HTTP/1.1: Success (0.000 secs)

Notice the puzzling "Success" as the error explanation.

We have 2 different "services" behind pound -- lighttpd for static files
(marked as YYY in the log above), and Apache with mod_perl (XXX in the
log)[...]