I covered all holes and blocked back fan with paper clip when the error changes to overheat i think 3 red rings. you can boot up the system agian (remove tape and paper clip). E74 should go away and you can play. (But sooner than later it will be unfixable with this method.)

if you have tryed al the above^^^^

then you have 2 options you can ether fix it your self with an X-CLAMP kit (it is the CPU or the GPU which has overheated not sure which one but yeh...)

Or you can just send it back to Microsoft for FREE, as there is a new 3 YEAR EXTENTION WARRANTY which covers the E74 and 3 red lights

I would personally send it to Microsoft it will take 1-2 weeks....

hope this helped

Tried all of those things.
I think its something too do with AV.
But its not my AV cable because i tested it with another.

Thanks for the ideas though guys

But coos
I have opened it and Microsoft dont take xbox's that have been opened?
What is this X clamp thing?

go n youtube and just search it and there are tutorials on hw to fix E74...

+ go on eBay for the X-CLAMP kit

try rebooting your system without your hard drive plugged in a see what happens

I've decided im sending it too a shop near my house.
Will cost 40 pound to get it fixed but it's worth it.
Thanks all for the help