ID: Q171631
The information in this article applies to:
WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.
When you try to compile a Java class using JVC (Microsoft's Java compiler), you may receive the following error message:
   error J0051: Undefined package 'java.lang'
This behavior is caused by the Classes.zip file not being present after you install Internet Explorer.
WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall Windows. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.
NOTE: For information about how to edit the registry, see the online Help in Registry Editor.
To resolve this issue, follow these steps:
1. Click Start, and then click Run.
2. Type "clspack -auto" (without quotation marks) in the Open box, and
   then click OK.
   NOTE: This process can take up to two minutes, and during this time no
   progress indicator is visible.
   compile, continue to the next step.
   the key is present, verify that it has the value listed below. If
   needed, edit the value to match the value listed below. If the key is
   not present, create it with the value shown here.
      HKEY_LOCAL_MACHINE\Software\Microsoft\Java VM\Classpath
         <windir>\java\classes\classes.zip
   Note that <windir> is the folder in which you have Windows 95 or
   Windows NT 4.0 installed.
Keywords          : kberrmsg msiew95 msient 
Platform          : WINDOWSLast Reviewed: March 19, 1999