Does the opera browser has caches when I view the web pages?
Yes, Opera caches web pages. You'll find them here: Tools/Preferences/Advanced/History. You can also empty the cache there.
Have you tried to reload a page/frame.
... sometime I could only see partial configuration page with all buttons
were missing and the browser was busy to waiting something ...
In my experience, when Opera loads a page and encounters an error,
if you try to reload that page, it keeps busy waiting forever.