Its quite hard to explain, in a simple title, the cause and solution to this problem. If you have ever run an X11 or Java program (or both at the same time) you may find that the program doesn’t run, or appears with a random error. I have also seen problems where the program in question runs, but all of the text is garbled. I first found this problem when trying to install MATLAB, the program wouldn’t run after the installer. The solution is rather simple and I assume it is transferable to other applications. This post may be very specific and you may not needed it, however if you ever come across a problem which involves X11 and Java keep this post in mind.
The problem occurs with applications for Java. If you try to run an application which only supports the 32-bit mode for Java, it will run into problems. In theory 32-bit applications should run on 64-bit packages fine. However when you are running applications though X11 or the applications in question is a bit picky you may find the application doesn’t run. To solve this problem we need to change how Java runs. This could be done through a really complicated Terminal command and make this post look complicated, but Apple have kindly provided a mini app to do this for us.
Go to Applications > Utilities and open up Java Preferences, this app may seem obvious now, but when I tried to install MATLAB, I had know idea it existed. Within this app you can change which package your OS will run. In the bottom half of the window move the 32-bit option to the top of the list then close the app.
When you close the app the changes will take effect. Hopefully any old Java and X11 apps should now run (assuming they use Java). Its only a small and simple trick however it helped solve the problem I was having. In the future when you come across an app and it clear isn’t working correctly this may be your solution. You can also change the settings for the plugins for web browsers, if you are having trouble there.