PROBLEM SOLVED!!!
KUDOS to anon for providing the solution! Just yesterday I had my x-box over at a friends house. When I took it back home and tried to switch it on, it booted three times, the two first with a green light, the third time freezing in red/orange flash. Screen was black. However, if I pressed the eject button while the box was doing it's red/orange flash routine, I would get a small green blob on screen (frozen), and the boot-sound would play. As I remember my dvd-player could eject. I have spent all day reading on the net to see if anyone had encountered the same problem, finally reading this thred to see if any suggestions were offered. Interestingly nobody seems to have tried anon's tutorial for fixing this problem before. I followed his (or her?) instructions, and the box is now working properly! I did not bother to remove my pogo-pin installed chip to verify his theory that sloppy removal of soldier can be the cause of the problem. I cannot see how sloppy removal of soldier can leave the box working properly for four months before suddenly comming to a halt, but it would explain why this problem only seems to occur to v1.0 x-boxes. Well, there you go all of you, get out your soldering irons and get to work;)
Oh, and if you missed anon's tutorial, you can find it here:
Anon's turorialHappy soldering everybody!
-fredped