I've a Sandisk Sansa e280 MP3 Player. The Mplayer is charged via USB cable. To charge the player 
I've connected the Player to my FreeBSD Workstation. After charging the Player (ca 2h) I disconnected the Player
and get the following Message 

umass0: BBB reset failed, IOERROR
umass0: BBB bulk-in clear stall failed, IOERROR
umass0: BBB bulk-out clear stall failed, IOERROR

repeating every two secounds. The umass device has never been mounted during the charge time.  

The player is an MTP device and has an entry in my hal policies. 

      <!-- SanDisk Sansa e200/e250/e260/e270/e280 -->
      <match key="usb.vendor_id" int="0x0781">
        <match key="usb.product_id" int="0x7420">
          <match key="info.capabilities" contains_not="portable_audio_player">
            <append key="info.capabilities" type="strlist">portable_audio_player</append>
          </match>
          <merge key="info.vendor" type="string">SanDisk</merge>
          <merge key="info.product" type="string">Sansa e200/e250/e260/e270/e280</merge>
          <merge key="info.category" type="string">portable_audio_player</merge>
          <merge key="portable_audio_player.access_method" type="string">user</merge>
          <match key="portable_audio_player.access_method.protocols" contains_not="mtp">
            <append key="portable_audio_player.access_method.protocols" type="strlist">mtp</append>
          </match>
          <append key="portable_audio_player.access_method.drivers" type="strlist">libmtp</append>
          <match key="portable_audio_player.output_formats" contains_not="audio/mpeg">
            <append key="portable_audio_player.output_formats" type="strlist">audio/mpeg</append>
          </match>
          <match key="portable_audio_player.output_formats" contains_not="audio/x-ms-wma">
            <append key="portable_audio_player.output_formats" type="strlist">audio/x-ms-wma</append>
          </match>
          <merge key="portable_audio_player.libmtp.protocol" type="string">mtp</merge>
        </match>
      </match>
      <!-- SanDisk Sansa e280 -->
      <match key="usb.vendor_id" int="0x0781">
        <match key="usb.product_id" int="0x7421">
          <match key="info.capabilities" contains_not="portable_audio_player">
            <append key="info.capabilities" type="strlist">portable_audio_player</append>
          </match>
          <merge key="info.vendor" type="string">SanDisk</merge>
          <merge key="info.product" type="string">Sansa e280</merge>
          <merge key="info.category" type="string">portable_audio_player</merge>
          <merge key="portable_audio_player.access_method" type="string">user</merge>
          <match key="portable_audio_player.access_method.protocols" contains_not="mtp">
            <append key="portable_audio_player.access_method.protocols" type="strlist">mtp</append>
          </match>
          <append key="portable_audio_player.access_method.drivers" type="strlist">libmtp</append>
          <match key="portable_audio_player.output_formats" contains_not="audio/mpeg">
            <append key="portable_audio_player.output_formats" type="strlist">audio/mpeg</append>
          </match>
          <match key="portable_audio_player.output_formats" contains_not="audio/x-ms-wma">
            <append key="portable_audio_player.output_formats" type="strlist">audio/x-ms-wma</append>
          </match>
          <merge key="portable_audio_player.libmtp.protocol" type="string">mtp</merge>
        </match>
      </match>
      <!-- SanDisk Sansa e280 v2 -->
      <match key="usb.vendor_id" int="0x0781">
        <match key="usb.product_id" int="0x7422">
          <match key="info.capabilities" contains_not="portable_audio_player">
            <append key="info.capabilities" type="strlist">portable_audio_player</append>
          </match>
          <merge key="info.vendor" type="string">SanDisk</merge>
          <merge key="info.product" type="string">Sansa e280 v2</merge>
          <merge key="info.category" type="string">portable_audio_player</merge>
          <merge key="portable_audio_player.access_method" type="string">user</merge>
          <match key="portable_audio_player.access_method.protocols" contains_not="mtp">
            <append key="portable_audio_player.access_method.protocols" type="strlist">mtp</append>
          </match>
          <append key="portable_audio_player.access_method.drivers" type="strlist">libmtp</append>
          <match key="portable_audio_player.output_formats" contains_not="audio/mpeg">
            <append key="portable_audio_player.output_formats" type="strlist">audio/mpeg</append>
          </match>
          <match key="portable_audio_player.output_formats" contains_not="audio/x-ms-wma">
            <append key="portable_audio_player.output_formats" type="strlist">audio/x-ms-wma</append>
          </match>
          <merge key="portable_audio_player.libmtp.protocol" type="string">mtp</merge>
        </match>
      </match>

Fix: 

n/k
How-To-Repeat: connect and disconnect the player