I have exacting the same problem in windows 7, 64 bit. I downloaded arduino-1.8.5.zip for Windows and unzipped. When I run arduino_debug.exe I get the same errors:
c:\arduino-1.8.5>arduino_debug.exe
Looking for library 'user32'
Adding paths from jna.library.path: null
Trying user32.dll
Found library 'user32' at user32.dll
DPI detection failed, fallback to 96 dpi
Looking for library 'shell32'
Adding paths from jna.library.path: null
Trying shell32.dll
Found library 'shell32' at shell32.dll
Looking for library 'Ole32'
Adding paths from jna.library.path: null
Trying Ole32.dll
Found library 'Ole32' at Ole32.dll
Looking for library 'kernel32'
Adding paths from jna.library.path: null
Trying kernel32.dll
Found library 'kernel32' at kernel32.dll
com.sun.jna.platform.win32.Win32Exception: The system cannot find the file speci
fied.
at com.sun.jna.platform.win32.Shell32Util.getFolderPath(Shell32Util.java
:48)
at com.sun.jna.platform.win32.Shell32Util.getFolderPath(Shell32Util.java
:61)
at cc.arduino.os.windows.Win32KnownFolders.getDocumentsFolder(Win32Known
Folders.java:71)
at processing.app.windows.Platform.recoverDefaultSketchbookFolder(Platfo
rm.java:76)
at processing.app.windows.Platform.init(Platform.java:55)
at processing.app.Base.(Base.java:201)
at processing.app.Base.main(Base.java:144)
c:\arduino-1.8.5>