Yes there is a problem with the Humax 4000T rebooting since the last update, hopefully Humax will sorted soon. There is a lot about it on here just check other threads (topics).
Thus afternoon I was watching a recording when my FVR400T switched itself off. After a few attempts I managed to switch it on again, but while waiting for the recordings to reappear it switched off again. Since then it has repeatedly been switching itself on every half minute or so and then off after about 4 seconds – more than half an hour now without me going near it.
My problem turned out to be nothing to do with Humax – when I eventually switched to tv there was no signal. I checked the aerial connections and found the one between Humax and tv wasn’t working. Luckily I had a spare in my box of cables, and all is now well!