After install Quartus II SP2 it stop working. When you execute Quartus a blank window appears. This problem seems related to the graphical interface. I found two solutions that work on my environment (Linux Mint 8 64 bits (an Ubuntu-based distribution)):
1) a simple work-around is execute a QT GUI version of Quartus II. Just execute "qgui" instead of "quartus". But this is a beta interface.
or
2) copy "mw" and "mw64" directory from previous Quartus II to location where you installed it.
