Ha! I had the E74 error last December on my 360, E74 is said is worse than the RROD itself , when I had it I was like WTF without no reason I had a red light by turning my 360 on the first time taht day, I did everything to figure out what was wrong, I booted my 360 without the harddrive I checked the wires I turned on and off many times and nothing..
I called Microsoft and asked them what E74 was they didnt have a direct answer for what it meant E73 means faulty harddrive and they said is probably the same problem, so after many research its Said E74 means a faulty Ethernet port, so I said to myself how can an ETHERNET port go bad? so I called Microsoft again to see what they can do about it, so they checked if I had warranty, mind you I bought my 360 nov 07 and this happen dec 08, when they got back to me they said I had no warranty so I said didnt MICROSFT extended the warranty to 3 years? and they said yeah but 3 years for the 3 red rings not for one red light, now you have to bring it in for repairs and that will cost $100, I said for that I buy me a new Arcade model for another $100..
So than I took matters into my own hands and started googling and you tubing and found that I was not the only one with this prob and found out that the prob was related to overheating.. So I did the X-clamp mod to my 360, I removed the X-clamp and heatsinks applied heavy duty thermo compound and screwed back in the heatsink plus on top of that I added 3 pc fans modded to run at a constant 12v including the stock fans...Now my 360 is working better than ever..
Note no matter what prob you get with your 360 is most related to overheating, i
My Trigger Happy Sixaxis controller
