I'm dealing with PayPal in this post, but I also had a problem with at least one other site last night which drove me to Firefox.
So, it appears confirmed to be only a "Safari c/w reCaptcha" issue. The reCaptcha connection worked with FireFox in your case and, in mine, always works with Opera. I wonder if it could be connected to Apple's focus on security. Does Safari see something in reCaptcha that rings an alarm bell, but that other browsers don't worry about?
