Version:           1.3 beta2 (using KDE KDE 3.4.1)
Installed from:    Compiled From Sources
Compiler:          version gcc 3.4.1  (Gentoo Linux 3.4.1, ssp-3.4-2, pie-8.7.6.3) 
OS:                Linux

With amarok 1.3_beta2, when I tag a file with MusicBrainz, amarok freezes. It occurs after the first tagged file or the second. The problem is systematic. I've compiled myself amarok 1.2_beta2 and taglib (the last one). My version of libtunepimp is correct (0.3).

The output is (in debug=full) :

amarok: Loading playlist
amarok: [ThreadWeaver] Job completed: PlaylistReader. Jobs pending: 0
amarok: BEGIN: virtual void Playlist::contentsDropEvent(QDropEvent*)
amarok:   [Playlist] QTextDrag::subtype(): uri-list
amarok:   [Playlist] KURLDrag::canDecode
amarok:   BEGIN: UrlLoader
amarok:     BEGIN: UrlLoader::UrlLoader(const KURL::List&, QListViewItem*, bool)
amarok:       [KDE::ProgressBar::ProgressBar(QWidget*, QLabel*)]
amarok:       [StatusBar] Creating timer for: 1updateProgressAppearance()
amarok:     END__: UrlLoader::UrlLoader(const KURL::List&, QListViewItem*, bool) - Took 0.042s
amarok:   END__: virtual void Playlist::contentsDropEvent(QDropEvent*) - Took 0.07s
amarok:   [StatusBar] 1updateProgressAppearance()
amarok:   [static void GstEngine::candecode_handoff_cb(GstElement*, GstBuffer*, void*)]
amarok:   [static void GstEngine::candecode_handoff_cb(GstElement*, GstBuffer*, void*)]
QObject::connect: Cannot connect QSignal::signal(const QVariant&) to (null)::(null)
QObject::connect: Cannot connect QSignal::signal(const QVariant&) to (null)::(null)
QObject::connect: Cannot connect QSignal::signal(const QVariant&) to (null)::(null)
amarok: [void TagDialog::musicbrainzQuery()]
amarok: [virtual void KTRMLookup::collision()] /hdf/mp3/Nick Cave & The bad seeds - The boatman's call/track15.cdda.ogg
amarok: eTrackList
amarok: [void TagDialog::fillSelected(KTRMResult)]
amarok:   [CollectionDB] sqlite3_step: BUSY counter: 1
amarok:   [CollectionDB] sqlite3_step: BUSY counter: 2
amarok:   [CollectionDB] sqlite3_step: BUSY counter: 3
amarok:   [CollectionDB] sqlite3_step: BUSY counter: 4
amarok:   [CollectionDB] sqlite3_step: BUSY counter: 5
amarok:   [CollectionDB] sqlite3_step: BUSY counter: 1
amarok:   [ThreadWeaver] Job completed: UrlLoader. Jobs pending: 0
amarok: END__: UrlLoader - Took 16s
amarok: [StatusBar] Creating timer for: 1hideMainProgressBar()
amarok: [void CollectionView::renderView()]
QObject::connect: Cannot connect QSignal::signal(const QVariant&) to (null)::(null)
QObject::connect: Cannot connect QSignal::signal(const QVariant&) to (null)::(null)
QObject::connect: Cannot connect QSignal::signal(const QVariant&) to (null)::(null)
amarok: [virtual KDE::ProgressBar::~ProgressBar()]
amarok: [StatusBar] 1hideMainProgressBar()
amarok: [void TagDialog::musicbrainzQuery()]
amarok: [virtual void KTRMLookup::collision()] /hdf/mp3/Nick Cave & The bad seeds - The boatman's call/track14.cdda.ogg
amarok: eTrackList
..... frozen .....

And with gdb :

(gdb) bt
#0  0xb677cd82 in __pthread_sigsuspend () from /lib/libpthread.so.0
#1  0xb677c389 in __pthread_wait_for_restart_signal () from /lib/libpthread.so.0
#2  0xb6778d9b in pthread_cond_wait@GLIBC_2.0 () from /lib/libpthread.so.0
#3  0xb682541f in Semaphore::wait() () from /usr/lib/libtunepimp.so.2