Andrew - As with most electronic devices that have at least a bit of sophistication, they will have an operating system running in their RAM (Random Access Memory). When the device's power is completely shut off, its RAM goes dead which clears out the corrupted operating system. Sometimes for reasons like a power surge or power starvation, whatever the cause can be, the operating system program can get corrupted and confused. Many times to fix that, turning off the power will force the device to reload a fresh and uncorrupted copy of its operating system from the ROM (Read Only Memory) to the RAM. IT techs call this powering off and back on "forcing out the Gremlins."