Hello,
I too have same problem as above. No sound on being called, only lights and vibration. I had nothing extra installed, I don't use the headphone.
I've tried all above suggestions, without succes.

On cp /opt/maemo/usr/lib/libFLAC.so.8.2.0 /usr/lib/libFLAC.so.8.2.0 I get error message cp: cannot stat ' /opt/maemo/usr/lib/libFLAC.so.8.2.0': No such file or directory

on start pulseaudio it returns -sh: start: not found

I went so far to flashing twice, still no sound on being called. Having flashed, there is no extra software, still the speaker gives muted sign.
Please help, for the phone is useless this way.