The E74 error message indicates either a problem with the GPU's solder connections or a fried AV-chip (due to cable connecting/unconnecting while the Xbox 360 and/or the TV was powered-on).
You have to send the Xbox 360 in.
There are DIY methods like putting the motherboard into a cooking oven to "reflow" the GPU's solder connections but most likely the Xbox 360 will fail again soon.
A.R.S.
November 2012
Right then the main issue is with your motherboard, most likely the av port on your xbox is having a fit. There are ways to open up your newly aquired white paperweight but to be honest if you dont know your way around an xbox DO NOT attempt repair. Have a look at the worlds biggest video clip website mentioning no names. There are several issues regarding this potentially fatal error message.
Andrew Howe
June 2008
Automatic Answer
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