Even I faced this problem while accessing a learning application from Thomson Learning. Looks like the application is not able to access the JAR containing the class or the Class file itself is missing.

Exception in thread "Thread-36" java.lang.NoCla ssDefFoundError : intellipro/utils/IP2DPlot
at java.lang.Class .getDeclaredMet hods0(Native Method)
at java.lang.Class .privateGetDecl aredMethods(Unk nown Source)...