xscreensaver: Can't open display: :0
xscreensaver: running as user/user (1000/1000)
 
xscreensaver: Errors at startup are usually authorization problems.
              But you're not logging in as root (good!) so something
              else must be wrong.  Did you read the manual and the FAQ?
 
              http://www.jwz.org/xscreensaver/faq.html
              http://www.jwz.org/xscreensaver/man.html