Hi. I haven't seen this myself, though about a week ago a friend reported that the UI froze "a couple of times." Since you experience it frequently, we might be able to find what's causing it.
apt-get install libqt4-dev libasound2-dev quilt Review and run the attached script. It will compile and run lastfm with a lot of debug info. Once you start having problems, see if you can close the client normally so we can get gprof info. After the client closes, edit ~/lastfm-debug/lastfm-output.log to hide your username and password hash. You may also wish to edit container.log; it only contains your username. gzip ~/lastfm-debug/*.log and send them to me. Maybe valgrind might give some interesting info? I don't know. Finally, have you noticed any patterns? For instance, does it happen more frequently if scrobbling is active, or if the stream is frequently interrupted?
lastfm-debug.sh
Description: application/shellscript
