It won't matter much to the end result, but... you've posted in the 360 board but have referred to a TiVo. They're completely different boxes, so can you confirm which you have? If you're not sure, check here . If forum staff pick this thread up, it'll certainly help to be sure.
Regardless of the answer, a box that's rebooting itself is faulty - it shouldn't be happening. You can report box faults by calling VM on the usual number (150 from a Virgin phone, or 0345 4541111 from any other phone), or by waiting on here for VM staff to pick it up.
The latter may take a day or so, and it will certainly help if you can confirm the box you have.
I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more
Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks