What is the exact error message that you are seeing? Have you ensured the date and time on your PC are correct?

See:

• Firefox/Tools > Options/Preferences > Advanced > General : Accessibility : [ ] "Warn me when web sites try to redirect or reload the page"

The setting in "Tools > Options > Advanced > General" is meant as an accessibility feature, as you can see by the label of that section, so that people with disabilities or people who use screen readers do not get confused and is not meant as a safety protection to stop redirecting.

See also:

• https://support.mozilla.org/kb/settings-network-updates-and-encryption#w_general-tab

• http://kb.mozillazine.org/accessibility.blockautorefresh
• http://kb.mozillazine.org/Accessibility_features_of_Firefox

I have unchecked this option and now it is OK. But your explanation what is the intention does not feel as a clarifying. It just adds one more complication to the many options and settings in FF, rising the learning threshold.

This is an accessibility setting in Firefox as you can see from the Accessibility heading under which it appears.
Firefox has a lot of settings to improve the readability of websites for people with disabilities, but most are only accessible via the about:config page.

• https://support.mozilla.org/kb/accessibility-features-firefox-make-firefox-and-we
• http://kb.mozillazine.org/Accessibility_features_of_Firefox

• http://www.w3.org/WAI/intro/people-use-web/Overview.html
• http://www.w3.org/WAI/intro/people-use-web/diversity

Most of those many settings do not have much of a usage in spite of its intentions to be usefull, they only make FF very complicated. Compare to Safari, it has not so many settings yet it is just as usefull as FF (with slight differences)