No sound

the same happened to me, here is what --verbose says:

pithos -v
INFO - pithos:<module>:828 - Pithos 0.3.17
/usr/bin/pithos:805: GtkWarning: Ignoring the separator setting
  builder.add_from_file(ui_filename)
INFO - plugin:enable:35 - Enabling module scrobble
INFO - plugin:enable:35 - Enabling module notify
INFO - plugin:enable:35 - Enabling module notification_icon
INFO - plugin:enable:35 - Enabling module mediakeys
INFO - mediakeys:bind_dbus:32 - Bound media keys with DBUS
INFO - pandora:connect:172 - Time offset is -0.452764987946
INFO - pithos:pandora_ready:328 - Pandora connected
INFO - pithos:process_stations:348 - Restoring saved station: id = 222948277776515275
INFO - pithos:station_changed:541 - Selecting station 222948277776515275; total = 25
INFO - pandora:get_playlist:247 - pandora: Get Playlist
INFO - pithos:start_song:386 - Starting song: index = 0
/usr/lib/python2.7/urllib.py:1268: UnicodeWarning: Unicode equal comparison failed to convert both arguments to Unicode - interpreting them as being unequal
  return ''.join(map(quoter, s))
Unhandled exception in worker thread:
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/pithos/gobject_worker.py", line 34, in _run
    result = command(*args)
  File "/usr/lib/python2.7/dist-packages/pithos/pylast.py", line 3635, in report_now_playing
    _ScrobblerRequest(self.nowplaying_url, params, self.network).execute()
  File "/usr/lib/python2.7/dist-packages/pithos/pylast.py", line 3537, in execute
    value = urllib.quote_plus(self.params[name])
  File "/usr/lib/python2.7/urllib.py", line 1273, in quote_plus
    s = quote(s, safe + ' ')
  File "/usr/lib/python2.7/urllib.py", line 1268, in quote
    return ''.join(map(quoter, s))
KeyError: u'\xe1'

INFO - pithos:art_callback:468 - Downloaded album art for 0
INFO - pithos:art_callback:468 - Downloaded album art for 2

I don't know if it has to do with the error or not. because closing and opening pithos even doesn't sometimes help.

I can confirm this issue as well. I have verfied it on Debian, Ubuntu, Lubuntu and Crunchbang. Restarting does not alway resolve the issue.