Freezing or blocking occurs when the signal strength or quality are low, if you receive your signal from a satellite dish and all your connections are good, there are two common things to check for, the first is that a tree or bush has not grown in the summer to obstruct the line of site with the satellite, the second and possibly the most common cause is that the dish is out of line and no longer pointing accurately at the satellite, many things could cause this, a ball might have hit it, or someone walking passed with ladders (window cleaner). If you have two receivers in the property and one is working okay and the other is not then it is unlikely to be a dish problem, to be sure try swapping the location of the receivers, if the issue follows the box, then this is where your issue lies, if not then it may be the lnb (feed horn) or cabling.