iPhone & Provider Sites

Other than Flash videos, I have no problems viewing websites on my iPhone. Recently, I have noticed that certain provider sites do not display correctly. Specifically, I am not able to scroll down. The websites appear as if I am viewing a screen dump of their website.

Are these websites using Flash?

I know on certain web sites I had to held the phone vertically
to able to scroll down.

Normally the phone is held vertically.