bad plugin within PLugins direfctory > Illustrator Formats > FXGFileFormat.aip
Removed plugin and now it works.
You can go ahead and install the JAVA update from the Apple by going to link below:
Once that is downloaded please go ahead and put the FXGfileformat.aip & launch illustrator and it should work for you.
If that doesnt work try to reset the prefrences for Illustrator.
Press and hold Option+Command+Shift (Mac OS) as you start Illustrator. Your current settings are deleted.
Let me know if you need further help on this.
I'm also having this problem - I tried the fix above and it still doesn't work. The icon bounces in my dock, then stops bouncing. The Icon appears inactive in the doc (ie doesn't have an active state) but I have to force quit the application.