I entered a question, had no problem with the Captcha, went back to edit it, but edit will not save because Captcha always fails (have tried like 30 times).
If you sign in, then you won't be presented with a captcha challenge.
Incidentally, I've had it fail for me many times, and I tracked it down to the system not the browser. Never bothered to figure out what system restriction was screwing it up other than the ones that work are the least hardened.
Do you still have this issue? We've recently fixed set of issues related to CAPTCHA, so it should be all working now. Please contact me directly if you need further assistance. Thanks.