Recently I added the option to signon to one of my wife's website with Facebook. I used the PHP SDK from Facebook, basically I took the two PHP files merged them in one, place them in to the helper section of code ignitor project, and added it to the auto load section. This was going fine until I moved to my wife's compute and tried it under FireFox and failed. Hum, now I know this should not be a FireFox problem and since it worked in the other three major browser was having trouble coming up with a reason why it was not a FireFox problem.
Oh well after a hour of fighting with this I noticed that whenever I enter the website URL FireFox would remove the WWW. A light turned on at that point, I then switch to the other browser and removed the WWW and yes they all failed. I moved to the FaceBook app section for the app and added a second URL, one WWW and one with the WWW, another failure.
So not wanting to fight with it any longer and having been told for SEO it was better to only have one version of your website either with or without the WWW and since the WWW version worked I added a section to the .htaccess file which forced all request to the WWW version. Guess what the site now has FaceBook login working correctly in all the browser.
You have got too love technolgy, grr!
first test
second test
third test