I honestly don't see how anyone could think a bug about Banshee could be duplicate of a *Rhythmbox bug*!!!

If there is not enough information in a bug, you ask for more information, you don't just send it into the thickets.

I'm seeing this also. I just upgraded from 10.10 to 11.04, which seems to have replaced Rhythmbox with Banshee as the default music player. However, it won't start. The main screen is displayed for a second and then disappears again.

This is on 11.04 (obviously) 64-bit, just upgraded from 10.10. I'm using the NVidia proprietary video driver.

Here is the console output from running banshee in a terminal:

[Info  13:46:13.136] Running Banshee 2.0.0: [Ubuntu Natty (development branch) (linux-gnu, x86_64) @ 2011-04-18 16:18:52 UTC]
[Info  13:46:13.997] Updating web proxy from GConf
[Info  13:46:14.065] All services are started 0.766405
** (Banshee:2626): DEBUG: SyncDaemon already running, initializing SyncdaemonDaemon object

(Banshee:2626): libsoup-WARNING **: No feature manager for feature of type 'U1RequestChrome'

** (Banshee:2626): WARNING **: Error calling get_info: Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.7/dbus/service.py", line 702, in _message_cb
    retval = candidate_method(self, *args, **keywords)
  File "/usr/lib/pymodules/python2.7/ubuntuone-client/ubuntuone/platform/linux/dbus_interface.py", line 992, in get_info
    return self.syncdaemon_folders.get_info(path)
  File "/usr/lib/pymodules/python2.7/ubuntuone-client/ubuntuone/syncdaemon/interaction_interfaces.py", line 634, in get_info
    mdobj = self.fs.get_by_path(path.encode('utf-8'))
  File "/usr/lib/pymodules/python2.7/ubuntuone-client/ubuntuone/syncdaemon/filesystem_manager.py", line 773, in get_by_path
    mdid = self._idx_path[path]
KeyError: '/home/pepijn/.ubuntuone/Purchased from Ubuntu One'


** (Banshee:2626): CRITICAL **: syncdaemon_folder_info_get_subscribed: assertion `SYNCDAEMON_IS_FOLDER_INFO (finfo)' failed

** (Banshee:2626): WARNING **: Error rescanning Purchased Music: No such file or directory
** (Banshee:2626): DEBUG: Loading the real store page

** (Banshee:2626): WARNING **: Got less number of items in credentials hash table than expected!
[Info  13:46:14.833] nereid Client Started
[Info  13:46:14.885] GStreamer version 0.10.32.0, gapless: True, replaygain: False
[Info  13:46:14.971] AppleDeviceSource is ignoring unmounted volume Windows Vista

Unhandled Exception: GLib.GException: Can't recursively copy directory
  at GLib.FileAdapter.Move (File destination, FileCopyFlags flags, GLib.Cancellable cancellable, GLib.FileProgressCallback progress_callback) [0x00000] in <filename unknown>:0 
  at Banshee.IO.Gio.Directory.Move (Hyena.SafeUri from, Hyena.SafeUri to) [0x00000] in <filename unknown>:0 
  at Banshee.IO.Directory.Move (Hyena.SafeUri from, Hyena.SafeUri to) [0x00000] in <filename unknown>:0 
  at Banshee.Podcasting.PodcastService.<DelayedInitialize>m__11 () [0x00000] in <filename unknown>:0 
[Info  13:46:14.996] AppleDeviceSource is ignoring unmounted volume Ubuntu (old)

Fortunately, Rhythmbox is still installed, and works properly. I don't know why the switch to Banshee was made, but the first signs aren't good...

Let me know what more information I can provide to help debug this problem!