digital box can some times have blocks, if your running this through your lcd screen.
have you tried a dvd to see how the screen looks, best way to test the screen quality .
lcd work well at hi res ,the dvd is the best way to check it.
another thing lots of low cost/quality lcd do have blocks , which is why i am doing my home work before buying a lcd tv.
its worth paying good money for one and to look at the screen at a shop before you buy.
always worth checking what screen looks like, as cr@p screen quality can really p ss you off.
as you found out.
some i’ve seen are really cr@p .
really want a lcd screen but the one i want isn’t down to my price yet.
any i hope you get it sorted