Well, die meant "became useless for practical purposes". Only three, then. I suppose one could argue that not having a SIM does not mean it can't be used. True. Still, for such drastic things to happen to your N900s is pretty awful, considering you are a 'champion'. I hope Nokia is prepared to give you another N900 or fix your current one so it can be used as a phone, as they gave you replacements for the others.

I have two N900s, neither of which has had such problems. I use one of them many times a day. I guess the other is my insurance.