Picture breakup & pixellation on live TV is often a symptom of a signal problem. Reboot your box once as a precaution, if it continues - you need to treat it as a fault.
Call 0800 5610061 to make sure there's no known issues in your area - if not, then you're best calling Virgin TV Faults to report your issue. 150 from a VM phone, or 0345 4541111 from any other phone, follow the prompts for "I have a fault with my TV service".
You're likely to need an engineer visit.
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