Because one of my N900s is now useless as a phone. My choice is to make use of the warranty, or just accept I can only use it as a tablet from now on. There is the other issue I had with the same N900 a couple of weeks ago with spurious graphical gliches, which persisted across several reboots. And although they stopped I get the feeling I can't trust the hardware in this N900 much longer, so I might as well make use of the warranty whether I get it replaced with a N900 or not. You may not value the warranty, but I do. And it will be the second time I've used the warranty for this N900, the first being for a broken USB port.

I'm well aware of the potential issue with the USB port having experience it first hand, but it still suits me to mitigate the risk through filing the hooks on the cable plug for the occasions I do have to use it, and using an external battery charger.