of us suddenly when we turn on our Xbox 360 console one day we got one
red light flashes on the ROL (Ring of Light) around the Xbox 360 power
button, and we got an Error message appearing on the TV screen "System
error" also might occur with any error code like E66, E67, E68, E71, E74
or E77, all the same.
you get any of these messages appearing on your screen with one red
light flashing on the ROL of your Xbox 360 console that's an indicator
of a hardware problem with the console connection to one of the parts
connected to it as the hard drive or cables.So, first disconnect all power and AV cables from the back of your Xbox 360 console and also unplug the power
cord from the wall socket, wait for a minute then reconnect them all back and try to turn on your Xbox 360 console once more.
that doesn't work, it seems then to be a fault with your Xbox 360 hard
drive so turn off the console again and remove the hard drive then turn
on your Xbox 360 console without the hard drive, supposed then to work
fine, it might be an intermittent issue and when you reconnect the hard
drive your Xbox 360 will work fine all after, or it will just work fine
without the hard drive so it will be then definitely a fault with your
Xbox 360 hard drive so call Xbox 360 customer support to exchange the
hard drive for you.
The Xbox 360 console might even keep giving
you the same error code even after you remove the hard drive so it will
then appear to be a fault with your Xbox 360 console not the hard drive
& also in a case like this we need to contact Xbox 360 customer
support to exchange the console.
Read more: http://xbox360help.blogspot.com/2007/03/one-red-flashing-light-xbox.html#ixzz14pQlSds6