JBuilder will disable your debug options if it is unable to locate the Java Platform Debugger Architecture (JPDA) classes for the JDK it runs on. In a default installation this should not be a problem. However, if you have changed the JDK that JBuilder runs on this problem may appear. The location of these classes is specified in the jdk.config file which can be found in the JBuilder bin directory. Look for a line in the file that looks like this:

addpath ../jdk1.3/lib/tools.jar

Make note of the path listed in your file and be sure that it points to a valid tools.jar . If it does not, correct it.