Frames you've run into before and know that you just about have to have them on to surf any length of time at all. You can control these options from Preferences-Documents. The new kid on the block is Inline Frames . They are a method of inserting external content on to the page seamlessly. You've probably seen them before and not even realized they were an inline frame.
Many modern sites use inline frames now for controlling dynamic content.
You probably will need these options checked. If you have messed around with the checkboxes under Preferences-Documents and goofed things up beyond recovery, it can adversely effect the way a page looks. A very common problem. That should get you back to usable working order. As you can see, Opera gives you an entire toolbox full of dials and knobs to get around problem sites.