Thank you for these answers. The whole installation was working since 2 years, and I have made no change at all. Since the problem has appeared, I'have tried to re install Mac OSX Leopard, and made all the sw update but no change: the wifi range is still poor.
- for me it is not a software issue.
What is strange is that when I am near the router the WIFI works just fine. I have a professionnal PC, and it still works from everywhere in the house, and it is the same with my iphone in WIFI. Can it be a problem with the wifi antenna which seems linked to the screen? Is there a way to put a third party pcmcia WIFI card?