Why Multiple java Console open while running the Applet application on JRE1.7.13 with IE8.

Our application is based on Applet. We are moving our project from JRE1.6 to JRE1.7 .13. On JRE1.6 we are able to compile and access the application. But after executing the application on JRE1.7.13 I am getting
java.lang.NullP ointerException
CNavBarDocument .<init>(CNavBar Document.java:4 0)
at sun.reflect.Nat iveConstructorA ccessorImpl.new Instance0(Nativ e Method)
at sun.reflect.Nat iveConstructorA ccessorImpl.new Instance(Unknow n...