A cookie!
Cookies will often cause browsers to reject access to web pages. If the “cookie” contains certain words or phases that the browser has been programmed to reject, you will not be able to get to these pages. For example my home page is www.excite.com, which is a legitimate cite (non porn), will not reload after running many of my malware, spyware, virus programs (because of the word “excite”). I have to go into the browser and give it permission to accept anything from www.excite.com.
Cookies are (not) our friends.