There's nothing special with regard to 32 bit or 64 bit. When you fire up the Console (typically via "java sim.display.Console"), one thing it does is try to determine all the simulation classes in your system. These classes are defined in a file called sim/display/simulation.classes and are listed by class name. Console tries to load each of these classes so it can display them in its list of available simulations. Sometimes when the Console loads a simulation class, an error is thrown, usually because Java can't find all the classes this class is referencing so it can't link it. This is what produces this error message (see line 1753 of Console.java) If you want a quick hack to prevent Console from printing this message, you could change line 1723 to read: boolean errout = true; // used to be false; Anyway, the #1 reason why Java can't find classes referenced by a simulation class is because it's referring to Java3D stuff and you don't have Java3D installed. But it's possible that there may be other reasons. I doubt the reason has anything to do with the bitness of your laptop or the particular Java virtual machine you've installed. Most likely you had Java3D installed before and now you don't. Here is a version of the simulation.classes file with the Java3D simulations removed. If this is still producing the error, then that'd be interesting.