i am facing the same problem for about 2 weeks now (and i've only received my kindle for less than 2 months) last night I decided to email amazon regarding the issue. this morning i woke up to a reply from them, asking me to call them for troubleshooting.
i called in and explained the situation to the representative, he said that since it is more of a hardware issue, there isn't much troubleshooting to be done. and that he'll be arranging a replacement for me.
international order
grrr
Update: there's some problem with my international shipping issue tho. have yet to receive the email after a representative summit a replacement order for me manually (coincidentally system wasn't happy when i called in) ...