Since about version 1.5.6, the last.fm plugin in banshee has been working very poorly (the last version that worked well for me is banshee_1.5.5+git20100307.r1.b1f45c7, right before much of the last.fm code was updated). Songs will stop playing halfway, or the next song does not start when switching (I can rarely play more than three song before this happens). When it happens, the affected song is marked by a cross. If I then double-click the next song, it will start to play again, but the song details don't update, making it appears as if the previous song is still playing. One thing I have noticed is that the progress bar indicating that the stream is buffering now appears for a much longer time. 

Thus far I managed to get around these problems by sticking with version 1.5.5+git20100307.r1.b1f45c7 in ubuntu 9.10, but I recently upgraded to 10.04 so this unfortunately isn't an option any more. I'm really hoping this problem can be resolved, since banshee is superior to rhythmbox in all aspects...

I am currently using banshee version 1.7.1+git20100626.r1.9c96586-0ubuntu1+lucid from the daily ppa, with an up to date Ubuntu Lucid install.