After a few months of use my Kindle started to freeze randomly. At first I blamed the cold as it happened to be winter in that moment. Fortunately, it turned out to be something different.
In fact, it’s the unlighted cover that wreaks havoc. One call at Amazon.com later I’ve got my refund + a $25 coupon. For more information, there’s an article at the Escapist Magazine.
There are still discussions going on whether the theory is correct or not, yet my Kindle didn’t crash since I don’t connect it to the pins anymore. Amazon seems to have fixed it by now and markets a new model, so if you have really such problems: Make sure you contact them.