FIX: Context menu under Windows 7 64 bit

src/platform/uosforms.pas

@@ -285,7 +285,7 @@ begin
       CoTaskMemFree(List);
     end;
 
-    DesktopFolder._Release;
+    DesktopFolder:= nil;
   end;
 end;
 {$ENDIF}

src/platform/win/ushlobjadditional.pas

@@ -1943,7 +1943,7 @@ begin
       CoTaskMemFree(ParentPidl);
     end;
 
-    DesktopFolder._Release;
+    DesktopFolder:= nil;
   end; // SHGetDesktopFolder
 end;