users on my forum have a problem with default Opera Browser settings. By default, Opera caches documents for 5 minutes. It's a problem when they use "view unread posts", click topic link with view=unread arguments in URL and when zero duplicate is enabled.
Script sends good url with 301 code and Opera store this url in cache. Everything is ok, if link directs to last page. If not, on next click to the same link, Opera will redirect user to read post, the same as the previous request.
In IE7-9, FF4-6 and Chrome stable everything is ok.
To prevent ...