I just signed up and have to admit I'm a bit relieved to read this post.
I took delivery of a 1100s yesterday. Set it up and it rebooted three times within a few hours. Then again last night. No freezing or anything just turns itself off then back on.
It also did it again this afternoon whilst I was watching iPlayer. I have done a factory reset then googled and found this thread.
I thought I'd got a faulty box so hopefully that's not the case and the issue will right itself.
Not the best introduction to freesat. This brand new box had rebooted more in 24 hours than my sky box has in 15 years. But I am glad to be free of the sky sub costs!