My Series 2 keeps restarting every 10 minutes

I have a series 2 that has run perfectly since last November.
For about a week now it has started shutting down and restarting about every 10 to 12 minutes. It does not matter what you are doing or even doing nothing and it restarts.

It is well ventilated, I am on a wired network connection and it is running SW version 3.3-01-2-540.

Reading through some forum entries both here and Tivo, there are suggestions about running an an Emergency reinstall of the software by inputting 52 while it is booting up. I think the instructions for this is written by the same guy on every site because he has a poor use of english and there must be more to do to get this to work because I've tried it many times and nothing happens.

I know that my hard drive may be bad but I want to try everything before I pay anything.

Is there anyone here that can please help me?

Thanks,

Jerry