My IAP does now support native IPv6. Then I have both the ipv4 and ipv6 on my system now and my hosts file contains: ::1 localhost 127.0.0.1 localhost /etc/mpd.conf have the following lines: bind_to_address "localhost" ---- Portage 2.1.4_rc11 (default-linux/x86/2007.0/desktop, gcc-4.1.2, glibc-2.7-r1, 2.6.23.12 i686) ================================================================= System uname: 2.6.23.12 i686 Intel(R) Pentium(R) M processor 2.00GHz Timestamp of tree: Wed, 26 Dec 2007 16:16:01 +0000 app-shells/bash: 3.2_p17-r1 dev-lang/python: 2.4.4-r4, 2.5.1-r4 dev-python/pycrypto: 2.0.1-r6 sys-apps/baselayout: 1.12.10-r5 sys-apps/sandbox: 1.2.18.1-r2 sys-devel/autoconf: 2.13, 2.61-r1 sys-devel/automake: 1.4_p6, 1.5, 1.6.3, 1.7.9-r1, 1.8.5-r3, 1.9.6-r2, 1.10 sys-devel/binutils: 2.18-r1 sys-devel/gcc-config: 1.4.0-r4 sys-devel/libtool: 1.5.24 virtual/os-headers: 2.6.23-r2 ACCEPT_KEYWORDS="x86 ~x86" CBUILD="i686-pc-linux-gnu" CFLAGS="-O2 -march=pentium-m -fomit-frame-pointer -pipe" CHOST="i686-pc-linux-gnu" CONFIG_PROTECT="/etc" CONFIG_PROTECT_MASK="/etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/revdep-rebuild /etc/terminfo /etc/udev/rules.d" CXXFLAGS="-O2 -march=pentium-m -fomit-frame-pointer -pipe" DISTDIR="/usr/portage/distfiles" FEATURES="distlocks metadata-transfer sandbox sfperms strict unmerge-orphans userfetch" GENTOO_MIRRORS="ftp://ftp.free.fr/mirrors/ftp.gentoo.org/ ftp://mirror.ovh.net/gentoo-distfiles/ " LANG="fr_FR.UTF-8" LINGUAS="fr" PKGDIR="/usr/portage/packages" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --delete-after --stats --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages --filter=H_**/files/digest-*" PORTAGE_TMPDIR="/var/tmp" PORTDIR="/usr/portage" SYNC="rsync://rsync.europe.gentoo.org/gentoo-portage" USE="X a52 aac acpi alsa apache2 audiofile bash-completion bitmap-fonts bzip2 cairo cddb cdparanoia cdr cli cracklib crypt cscope cups curl dbus dri dts dvd dvdr dvdread eds emboss encode evo exif fam ffmpeg fftw firefox flac gdbm gnutls gstreamer gtk hal iconv idn ipv6 isdnlog jabber javascript jpeg jpeg2k libnotify libsamplerate mad matroska midi mikmod mmap mmx modplug mp3 mpeg mudflap ncurses nls nptl nptlonly ogg opengl openmp pam pcre pdf perl png pppd python qt3support quicktime readline reflection session sndfile spell spl sse sse2 ssl startup-notification svg symlink theora threads tiff truetype truetype-fonts type1-fonts unicode vim-syntax vorbis wifi wxwindows x86 xcomposite xml xorg xv xvid zlib" ALSA_CARDS="hda-intel" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" ELIBC="glibc" INPUT_DEVICES="evdev" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="fr" USERLAND="GNU" VIDEO_CARDS="i810 none" Unset: CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LC_ALL, LDFLAGS, MAKEOPTS, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, PORTDIR_OVERLAY
Have you tried setting bind_to_address "::1" ? IIRC, mpd picks up ipv4 "localhost" by default when both are present... Or maybe it's last "localhost" entry, I'm not sure.
This has already been reported to upstream, btw - see http://musicpd.org/mantis/view.php?id=1517 and http://musicpd.org/mantis/view.php?id=1419
