A word of warning to the ignorers! If this message is caused by a website involving trust don't risk authorising anything or releasing private data! The same warning is issued when a real website has been successfully spoofed by criminals. One cause is benign, the other malicious.
Not good if your Bank is spoofed. The bad guys are keen to learn your login name, password, sort-code, account number and security answers. Even more delighted if you use them to transfer money. Never make it easy for evildoers!