Can't turn off devices

I downloaded and installed iOS 6 on both my iphone 4S and my ipad 2 yesterdsay. Everything seems to be working fine(ish), except I cannot turn off either device. When I hold down the wake/sleep button and the home button simultaneously, instead of getting the option to turn off the device, it appears to do a reboot. Anyone else experiencing this or have a suggestion on fixing it?

Thanks!