I have this same problem too (when trying to connect to the main Yahoo website of
www.yahoo.com). However, since I only to check my e-mail, I tried typing in the Yahoo mail address (mail.yahoo.com) and it was smooth sailing after that. So, I have that bookmarked as my Yahoo mail url now and unless you really need to check Yahoo for news or there lame video of the day, then just do what I did for e-mail. Sweet! It does kind of suck though that there is some issue with Yahoo not being able to protect or encrypt their main website url though.
I'm out!