Hi Adrian,
Any chance that reboot cycle is closer to three minutes? That's the sensor scan cycle for iOS and probably the most common cause of boot cycles.
You might try checking the panic logs; if it's a kernel panic causing your reboot the cause will be logged there and will be an invaluable clue toward figuring out what's going on with your iPad. @flannelist has written a Wiki article on kernel panics that you should take a look at. So far it's been focused on iPhones, but any device that runs iOS should be relevant.
[[iPhone Kernel Panics|iPhone Kernel Panics - iFixit|new_window=true]]
Assuming you find a panic log, post the first page of it in your question and we'll see if we can help diagnose the problem.