I had the same problem but it went away after performing the mods published
Here .
My sever (Where phpdig is) : Apache/1.3.28 (Unix) mod_auth_passthrough/1.8 mod_gzip/1.3.26.1a mod_log_bytes/1.2 mod_bwlimited/1.0 PHP/4.3.3 FrontPage/5.0.2.2634 mod_ssl/2.8.15 OpenSSL/0.9.7a on Linux.
I still have problems indexing a couple of servers running Netscape out of 265 servers with all kind of configurations.
Good Luck