That is very strange, I have never heard of that before. can you supply some additional details, are you watching a particular show? Is this 12:35 in the afternoon or evening? Are you seeing the "blue waves" with MTS logo? if you press a button does it go away? Does this happen on all set-top boxes or just one, if so which one?
Our Set Top Boxes are manufactured to meet or exceed Energy Star requirements, so they will go into Sleep Mode after 6 hours. Are you noticing this after turning it on at 6:35-6:45? If so, pressing one of the buttons on your remote will reset the Sleep Timer.