I too had ITV2 freezing, jittering, blanking etc only for a couple of seconds at a time but quite frequently (say every 5 or 10 minutes) last night when I was watching "Chancer" (don't laugh, I liked that series!
).
Most of the other main channels I checked around that time seemed OK.
Nothing unusual in the STB error log. I suspect the problem might have been at the source perhaps.