Error during JVM initialization occurred when class data sharing and compressed strings are used simultaneously:
>java -XX:+UseCompressedStrings -Xshare:dump
...
>java -XX:+UseCompressedStrings -Xshare:on -version
Error occurred during initialization of VM
java.lang.ExceptionInInitializerError
        at java.lang.Runtime.loadLibrary0(Runtime.java:819)
        at java.lang.System.loadLibrary(System.java:1028)
        at java.lang.System.initializeSystemClass(System.java:1086)
Caused by: java.lang.NullPointerException
        at java.io.UnixFileSystem.<init>(UnixFileSystem.java:21)
        at java.io.FileSystem.getFileSystem(Native Method)
        at java.io.File.<clinit>(File.java:127)
        at java.lang.Runtime.loadLibrary0(Runtime.java:819)
        at java.lang.System.loadLibrary(System.java:1028)
        at java.lang.System.initializeSystemClass(System.java:1086)

Issue introduced in jdk 6u23p-b03. It was found during jdk 6u35-b03 testing.