So we're going to try with strace this time.
This will probably help us solve the problem, but if it doesn't I'm not going to spend anymore time with it today, because I have other important issues to take care of during the rest of the week.
Next week I'll be at a conference untill Wednesday, so if the strace doesn't solve the problem... I will only look at it again by the end of next week...
Wish me luck