japitts listed all the channels that VM broadcast on the same frequency. If they had been pixellating the same as the BBC News HD channel then that would have indicated a signal fault. You may still have a box fault but that would only manifest if you had channels on other frequencies pixellating as well.
It may actually be a BBC issue, in my area there are no pixellations problems on the BBC News channel, however the sound is always lower than Sky News.
Have you tried watching the BBC News Channel live on the iPlayer?
Have you tried signing into Service status at the top of this page? It shows any local faults and you can also run a test against the TIVO/V6 box. By doing this VM if VM detect any issues they should be able to send a signal to your box and try to repair it, or send out a replacement and/or engineer.
If nothing is showing you could also try the Service Status number 0800 561 0061. This often gives details of more local issues down to postcode level.
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali
If the other channels on the same frequency aren't affected, then it only leaves a TX fault with that channel (which would affect large numbers of customers) or something else "odd" with your box.
Given that a likely end result here is a box-swap (for elimination purposes if nothing else) and you'll lose all your recordings, you're as wise to start working through the box reset cycles. Under Home > Help & Settings > Clear or reset TIVO box, there's several levels of reset. All have their own on-screen descriptions of what you'll lose and safety-net keypresses you'll need to follow.
If all this fails, then it's not a software issue and that only leaves a hardware swap.
I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more
Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks