Basic Cable Channels in HD are completely screwed up on all TVs in house

[channelstutter]

Basically what the title says. Traditionally Basic tv channels (ABC, NBC, Fox, CBS, PBS, etc) are screwed up (audio and video) when on the HD channels. Channels work in SD and all other HD channels are unaffected (except Hallmark Channel which gets it to a much lesser degree that is barely affected). Any advice on how to relieve this issue would be appreciated. 

[clem21]

First check all coax cables, make sure the connection is tight. Also could be a bad splitter. Rarely it's the ONT but a tech can check that remotely for you.

[Edg1]

If all TVs in the house are affected it is likely the ONT. Make sure all coax connections from the ONT to the STBs are tight. If no change then call Verizon to send a tech out to swap your ONT. 

[CRobGauth]

Is it only those channels (ie other HD are fine)?

Where are you located?

What model STBs do you have?

If VMS, it is possible that the VMS is bad (or has a bad connection) as all other STBs use a tuner in that box.