Well, I got to this thread--it's March 23, 2013--because for the last week I have been having all the problems people have mentioned--constantly having to relog onto Safari, and Firefox such a mess I can't even use it. (When I click on "show how this person is related to me", I may or may not get the relationship, but when I click again to show the chain of relationships, I get a blank box with "undefined". When I am linking to another tree, whenever I add information like place of birth, the auto-entry thing pops up, and sometimes it will just hang open until I click the matching information, and sometimes it has this huge message that begins "System:Net. Web exception_The underlying connection was closed. And unexpected error occurred on receive...". The message goes on and on and on. And then I can't add anything.)
I have called twice, and neither customer service person, pleasant as they were , acted as if they had ever heard of Macs having peculiar problems. They told me to clean out cache and cookies, which I did, on both browsers, and it helped on neither. I installed an upgrade to Java Script, which one swore would help. It did nothing. The second person told me if cleaning out cache and cookies didn't work it meant there was something wrong with MY computer, but they are the ones making constant changes to the site, I have not installed any new software, and have no other computer issues whatsoever on any other site in either browser.
I have Ancestry Deluxe and have been on the site for 12 years and I find the cluelessness of the customer help people about the problems on Macs a real dereliction of duty on Ancestry's part. I tried reading part of the message I get in Firefox as mentioned above--I had copied about half of it--but only got out about one sentence, as the person was clearly not even listening. "Yeah, yeah", though not in so many words. He just said to stop using Firefox--but a couple of years ago when I was having problems with Safari they told me to switch to Firefox, because it was a browser they supported and Safari was not! Now they say they support Safari--some support!
I feel as if the need to sign back in on Safari happens whenever I go to an external site through Ancestry--Find-a-Grave and the new image thing that has that National Archives logo.
UPDATE: It is now March 26, the constant sign-in problem on Safari is, if anything, only worse. I just don't have it in me to call Ancestry again for more useless advice, and the suggestion it's MY computer when it is clear it's an ANCESTRY problem with MACS really burns me up.