This bug report originated from Ubuntu's Launchpad bug tracker here: 

https://bugs.launchpad.net/rhythmbox/+bug/397028

and affects at least rhythmbox 0.12 and rhythmbox 0.11.6. The launchpad page has more details, but basically this streaming radio URL: 

mmsh://220.247.227.6/live?MSWMExt=.asf

has been causing reproducible lockups of rhythmbox. The original poster noticed this problem only during problems with his internet connection, but I noticed the problem immediately upon attempting to play this stream at the time. 

I tried the same URL again recently, and was able to play the stream fine, so I suspected the hanging might occur only when the streaming server is having problems, or when one's own internet connection goes down. To test this idea, I cut off my own internet connection in the middle of playing this stream. The music stopped, and 'top' showed rhythmbox using 100% of CPU. I attempted to un-press the play button, and the entire rhythmbox UI froze (i.e. the rb screen doesn't refresh itself anymore). I then had no choice but to forcibly kill rhythmbox. 

I ran the test again (I'm using rb 0.11.6) with the --debug option enabled. The stream played fine until I cut off the internet connection, and attempted to play a new song, at which point my debug output hung at the last line ("... [playing_source_changed_cb] rb-iradio-source.c:1187: disconnecting info-available signal handler"), and the player was frozen and I had to forcibly kill it again. 

Let me know if I should provide more details or help reproducing this bug. The tail end of rb's debug output is at bottom: 


(17:31:37) [0x9138408] [tick_cb] rb-shell-player.c:3613: tick: [mmsh://220.247.227.6/live?MSWMExt=.asf, 18:0(0)]
(17:31:37) [0x9138408] [tick_cb] rb-shell-player.c:3613: tick: [mmsh://220.247.227.6/live?MSWMExt=.asf, 18:0(0)]
(17:31:37) [0x9138408] [tick_cb] rb-shell-player.c:3613: tick: [mmsh://220.247.227.6/live?MSWMExt=.asf, 18:0(0)]
(17:31:37) [0x9138408] [rb_shell_clipboard_entryview_changed_cb] rb-shell-clipboard.c:787: entryview changed
(17:31:37) [0x9138408] [rb_shell_clipboard_sync] rb-shell-clipboard.c:585: syncing clipboard
(17:31:38) [0x9138408] [rb_entry_view_row_activated_cb] rb-entry-view.c:2070: row activated
(17:31:38) [0x9138408] [rb_entry_view_row_activated_cb] rb-entry-view.c:2074: emitting entry activated
(17:31:38) [0x9138408] [rb_shell_player_entry_activated_cb] rb-shell-player.c:2701: got entry 0xb4015070 activated
(17:31:38) [0x9138408] [rb_shell_player_set_playing_source_internal] rb-shell-player.c:3120: setting playing source to 0x981d8e0
(17:31:38) [0x9138408] [rb_shell_player_set_playing_source_internal] rb-shell-player.c:3143: source is already playing, stopping it
(17:31:38) [0x9138408] [rb_shell_player_sync_with_source] rb-shell-player.c:2936: playing source: 0x981d8e0, active entry: (nil)
(17:31:38) [0x9138408] [rb_shell_set_window_title] rb-shell.c:2141: clearing title
(17:31:38) [0x9138408] [rb_shell_player_get_playing_song_duration] rb-shell-player.c:3385: Did not get playing entry : return -1 as length
(17:31:38) [0x9138408] [show_controls] rb-visualizer-plugin.c:846: showing controls
(17:31:38) [0x9138408] [rb_shell_player_get_playing_song_duration] rb-shell-player.c:3385: Did not get playing entry : return -1 as length
(17:31:38) [0x9138408] [rb_header_sync] rb-header.c:452: syncing with entry = <null>
(17:31:38) [0x9138408] [rb_header_sync] rb-header.c:528: not playing
(17:31:38) [0x9138408] [rb_shell_player_sync_buttons] rb-shell-player.c:3039: syncing with source 0x981d8e0
(17:31:38) [0x9138408] [rb_shell_playing_source_changed_cb] rb-shell.c:1951: playing source changed
(17:31:38) [0x9138408] [playing_source_changed_cb] rb-iradio-source.c:1187: disconnecting info-available signal handler