Just the thought of a full reset on my Kindle gives me the shivers... it's what you can do when all else fails... when your Kindle is doing weird things (like locking up, or generally not doing what it should) and you just don't know what else to do.
It also erases everything on your Kindle and gives you a fresh start, if all goes well. A blank slate is not my first choice, especially if I have hundreds of books on my little machine.
Try a full shutdown and let your Kindle start up again instead. Slide the power switch to the Off position and hold it for 20 seconds (count if you have to). Release the power switch. You should see your Kindle blink and flash a bit, then turn off... then it will take its sweet time restarting.
When it comes back on, chances are very good it will have a whole new outlook on life.
Now these instructions may change for the newest Kindles when they make their appearance. I will certainly let you know if that is the case.