I don't know if this is a ComputerCraft issue or just a problem with the way Minecraft's chunk loading works:

Computers near the unload boundary will sporadically unload and reload, even if the player is not moving.

Reproduction steps

• Create a new world
• Lower the render distance to make chunks unload sooner
• Teleport out of the spawn chunks (\tp ~500 ~ ~)
• Place down a command computer with the following startup file

while true do
    commands.say(os.clock())
    sleep(3)
end

• Walk away from the computer, note the counter will increment.
• A chunk unload and reload will occur. The computer is destroyed and a new instance is created, the counter resets.

Further oddities:

• Pausing the game when the chunk is out of render distance will always cause this reload to occur.
• The computer does not "fully" unload until the full 9 chunks distance has been reached.
• Reloading the game whilst within this 9 chunk boundary will cause the computer to load and then unload again.

Screenshots