I try it with a new version with installer and the latest stable portable version and the nightly build and the latest beta.
I uninstalled everything and deleted the folder "C:\Users\Marph.000\AppData\Local\Arduino15".
But I still get this error, when I try to "add .zip-library" (Menu/Sketch/include library/add .zip library).

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at sun.awt.shell.Win32ShellFolder2.getFileSystemPath(Win32ShellFolder2.java:571)
at sun.awt.shell.Win32ShellFolder2.access$400(Win32ShellFolder2.java:72)
at sun.awt.shell.Win32ShellFolder2$2.call(Win32ShellFolder2.java:298)
at sun.awt.shell.Win32ShellFolder2$2.call(Win32ShellFolder2.java:296)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at sun.awt.shell.Win32ShellFolderManager2$ComInvoker$3.run(Win32ShellFolderManager2.java:556)
at java.lang.Thread.run(Thread.java:748)