FULL PRODUCT VERSION :
java version "1.7.0_55"

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]

A DESCRIPTION OF THE PROBLEM :
When running a webstart application which uses Corba (JacORB), the following exception is given.
org.omg.CORBA.INITIALIZE: can't instantiate default ORB implementation org.jacorb.orb.ORBSingleton  vmcid: 0x0  minor code: 0  completed: No
    at org.omg.CORBA.ORB.create_impl_with_systemclassloader(Unknown Source)
    at org.omg.CORBA.ORB.init(Unknown Source)
    at org.jacorb.orb.CDRInputStream.<init>(CDRInputStream.java:186)
    at org.jacorb.orb.etf.ProfileBase.initFromProfileData(ProfileBase.java:252)
    at org.jacorb.orb.etf.ProfileBase.demarshal(ProfileBase.java:172)
    at org.jacorb.orb.etf.FactoriesBase.demarshal_profile(FactoriesBase.java:124)
    at org.jacorb.orb.ParsedIOR.decode(ParsedIOR.java:235)
    at org.jacorb.orb.ParsedIOR.parse_stringified_ior(ParsedIOR.java:460)
    at org.jacorb.orb.ParsedIOR.parse(ParsedIOR.java:375)
    at org.jacorb.orb.ParsedIOR.<init>(ParsedIOR.java:192)
    at org.jacorb.orb.ORB.string_to_object(ORB.java:1824)

Caused by: java.lang.ClassNotFoundException: org.jacorb.orb.ORBSingleton
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)
    ... 56 more

This same application works when run outside of webstart.
The application does work in webstart with the previous version of Java (Java 7 update 51)



REGRESSION.  Last worked in version 7u51

ADDITIONAL REGRESSION INFORMATION: 
java version "1.7.0_51"

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Atttempt to initialise the client ORB of a corba application.


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
ORB initialises correctly
ACTUAL -
ClassNotFound exception is thrown.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
org.omg.CORBA.INITIALIZE: can't instantiate default ORB implementation org.jacorb.orb.ORBSingleton  vmcid: 0x0  minor code: 0  completed: No
    at org.omg.CORBA.ORB.create_impl_with_systemclassloader(Unknown Source)
    at org.omg.CORBA.ORB.init(Unknown Source)
    at org.jacorb.orb.CDRInputStream.<init>(CDRInputStream.java:186)
    at org.jacorb.orb.etf.ProfileBase.initFromProfileData(ProfileBase.java:252)
    at org.jacorb.orb.etf.ProfileBase.demarshal(ProfileBase.java:172)
    at org.jacorb.orb.etf.FactoriesBase.demarshal_profile(FactoriesBase.java:124)
    at org.jacorb.orb.ParsedIOR.decode(ParsedIOR.java:235)
    at org.jacorb.orb.ParsedIOR.parse_stringified_ior(ParsedIOR.java:460)
    at org.jacorb.orb.ParsedIOR.parse(ParsedIOR.java:375)
    at org.jacorb.orb.ParsedIOR.<init>(ParsedIOR.java:192)
    at org.jacorb.orb.ORB.string_to_object(ORB.java:1824)

Caused by: java.lang.ClassNotFoundException: org.jacorb.orb.ORBSingleton
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)
    ... 56 more

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Downgrade to older version of Java