Guys,
I had the same problem too. I took it to the Huawei authorised repair centre. They had the phone for few days to find out that the vibrator was faulty.
Occasionally when the phone vibrates, it resulted in an internal short circuit which ended up rebooting the phone. If the phone vibrates while rebooting, it goes back to restart mode again. They replaced the vibrator at free of cost.
Now I am one happy HUAWEI customer.
Hope this helps
Note: According to them, any internal damage could result in continuous reboot.