Cannot start Qsys from Quartus

I have installed Quartus 12.0 sp1 because I got a DE2i-150 board, which instructed me to do so. I also have 15.1 installed on the same machine. From 15.1 I can normally start Qsys, it just comes up. From 12.0, I cannot - when I click the Qsys icon or I want to create a new Qsys file (from the File menu) nothing happens, there are no errors and no messages. I have restarted the machine after installation and made sure that all of the environment variables (Windows 8.1) point to the 12.0 version of Quartus. Does anyone have an idea how to resolve this? Thanks!