NORTON internet Security 2011 deleted ALL C:Files

hi

        I just thought I successfully installed Norton 2011 Internet security on my Dell 1500 Inspiron with Vista.  I did a restart and my desktop wallpaper was changed to Windows Vista wallpaper default and every single file and program was wiped.It was like an unwanted complete OS re-install.

 

Before raping my other two PC's,  could someone please tell me what caused this and what's the work-around?

 

thanks!

Jim