Comment 15 for bug 226119

I ran across your post b/c I was looking for a solution for why my lastfm client stopped running with the same error you were having...

I fixed it and it was definitely caused by a third party app that installed an old version of libQt... in my cases nessus..

found it by typing:

ldconfig -v

saw:
/opt/nessus/lib:
        libQtGui.so.4 -> libQtGui.so.4.3.4
        libQtCore.so.4 -> libQtCore.so.4.3.4
        libQtXml.so.4 -> libQtXml.so.4.3.4

realized the "installed" version is 4.4.0

to fix, removed /opt/nessus from /etc/ld.so.conf

reran sudo ldconfig

fixed!

Hope this helps...