4 means the video cable is unplugged or something.
Apparently Microsoft are thinking about disabling the 4 rings warning because tons of working systems are being sent back just because the video cable wasn't connected.
(
Bloop Fri 16 Jul, 22:10,
Wed 15 Aug 2007, 23:48,
archived)
People are fail.
(
Shada,
Wed 15 Aug 2007, 23:55,
archived)