Some users are reporting problems launching EQMac v1.2.1 on older versions of Mac OS X including Snow Leopard (10.6.x) and Lion (10.7.x). It has been confirmed to work on Mountain Lion (10.8.x), which is the system I have used to produce the software. It is supposed to work on Snow Leopard and above, and I am working towards correcting this issue. I hope to have a fix in place sometime next week. In the meantime, you will likely find that older versions of EQMac will work ok, so please continue to use whichever version you can get to work until I can release a fix for this problem.