Some Kindle owners who purchased the non-lighted Kindle cover from Amazon have been having some issues with the eBook reader after using it. Many users are reporting that the covers are causing the eBook reader to freeze or reboot.
Speculation is that the metal hooks on the cover are the problem. They conduct electricity and are used to power the lighted case, however they are pretty useless for the non-lighted version. Amazon is looking into the problem and has agreed to replace the units.