I have several digital adapters, a Nextbox HD terminal box and a Nextbox 3.0 HDPVR box. The channels on the digital adapters are fine but several channels on both HD terminals now come up black. It started out as a couple but now includes 14, 15,17, 40,42,48, 50, 58 and others. Nothing has recently changed to either my equipment or my TV package. To test whether it was the fault of the wiring within my house, I connected one of the HD terminals with an HD TV directly after the amplifier where it enters my house and I had the same results. Is my only option to sit on the rogers helpline for an hour?
The issues you mention are almost always related to a poor signal. See the following post on how to check the signal yourself. If possible, remove the amp and any splitters and connect directly to the incoming cable. You may need a barrel connector. Talk to your neighbours in case it's a neighbourhood issue.