I haven't gone into Tapatalk for more than 2 weeks and just had to answer the challenge twice while logging in. I didn't reset (delete cookies or anything) on my browser. Using Chrome (version 29.0.1547.65) on a mac, jumped to safari (version 6.0.5) which I haven't logged into SMF for months and it gave me the challenge also. Sorry I can't help more.
2013 E350 EB-44, V10 6.8ltr
Toyo LT285/70 R17
I just tried to log on my iPad and am getting the same message as the other day...automatic log-in through Safari works but I still get the captcha. I did delete all previous tabs to start over from scratch but didn't delete an cookies (not sure how with Safari on an iPad).
'01 Ford EB50p Quigley 4WD