It sounds almost as if the buttons on the bezel may be reacting to something nearby (or internally). Register your television online (to get an extra three months for U.S. customers) and then see if you can get your unit inspected.
I've had my PN42A450 for over a year now with no issues at all. Yesterday it started acting up -- it basically looks like it's cycling through, getting continuous input. For example, if I have the cable input selected, it cycles continuously up from channel to channel -- 1, 2, 3, etc. If I select "menu" from the screen, it's continuously cycling through the options. It doesn't respond to the remote at all. And it I have it receiving input from our Tivo unit, it continuously displays " (i) Not available at this time."
Any ideas? Seems like if I could do a reset to the TV unit itself (without using the remote) it might do the trick. I've tried disconnecting everying (including the power) and leaving over night, hoping that it would reset, but to no avail.
Any ideas would be greatly appreciated!