Line 1 column one, this is what it says here.
** DO NOT EDIT THIS FILE.
** If you make changes to this file while any VirtualBox related application
** is running, your changes will be overwritten later, without taking effect.
** Use VBoxManage or the VirtualBox Manager GUI to make changes.
That hidden .VirtualBox folder just contains logs and config files that are updated & overwritten in use.
Maybe try and see if the Vbox installation is working by disabling the folder, say rename to .VirtualBox_bak then start VirtualBox either from the menu entry or in a console.
If it is working then the VBox Manager dialog, (without any VM's displayed) should show. A new .VirtualBox folder will be created.