Descriptive Problem Summary:
Problem is simple. Some of the websites pages cannot be scrolled down while using Opera to browse them.
Most common pages are blogs that use the default layout (I think it's the default layout)
These pictures explain it all.
Using firefox you can clearly see the page can be scrolled down.
Using Opera the page just cuts off. No scroll bar, Page up/down do not work on the keyboard, nothing can be done to scroll down the page, even though there is clearly more stuff down the page.