The latest Kindle 3 has exhibited a fault whereby either it reboots itself spasmodically while reading a book or it freezes just whilst switched on or on stand-by, thereby requiring a manual reboot.
This is regardless of whether its wireless is switched on or not. My Kindle was trouble-free and excellent for about the first 2 months until not long after I bought a standard Amazon leather cover for it. Not long after it developed this fault which over time it has got more frequent. A firmware upgrade did not cure the problem.
It is believed, both by users and Amazon support staff, that the cover might be the cause, because its bottom metal pin clips into a slot of the Kindle that also acts as an electronic interface.
This weekend I have removed the cover and have had no problem at all.
Amazon Kindle Tech guys are working on the issue urgently.
From the length of time it went without trouble, I'm sure it is not a software problem and no amount of upgrades will cure it.
All the indications that it is a hardware fault. It sounds as though the cover needs a condom over one of its appendages