I got this PM from one of my members:
hey there, ehm im having an issue with the captcha, no matter how many times i drag the right draw on the circle, its not saving any of the posts, what can i do about it? I’m using Firefox 22.0 on a Windows 8 Laptop
I don’t know what to tell them. I asked them if they had another browser that they could test with. However, I know Firefox to work very well with SP at least with Mac.
Please advise 
About the only thing I can think of is that they might have a particular Firefox extension that is causing some sort of clash. You might ask them to (1) try with a different browser just to see what happens and if that works OK to (2) deactivate their FF extensions to see what happens.
FF is my weapon of choice on PC too so I know it works well… Now I have chosen not to move that new crappy Windows 8 so cannot test it, but we have a fair number of users on it and have been no other reports..
might be worth noting if the user gets recognized as a mobile device or desktop when he browses (since windows now wants its win 8 devices to be agnostic)?