Having trouble logging into websites

Question

I have Mac Book Pro 10.8.4 and Safari 6.0.5. Ever since the most recent update, I have trouble logging into secure sites like Yahoo! mail, eBay to name a few. The login boxes are active but nothing happens when I hit the enter or signin button. It just sits there, it isn't hanging or anything like that, it's as if I'd hit any other place on the page where one wouldn't expect anything to happen. I can and do refresh the page, approach from a different "angle" (for lack of a better term, say from "sign in" instead of "mail" for example) and try again. Sometimes this is enough and sometimes it takes several attempts to get it to recognise my hitting the button. I didn't have trouble prior to this most recent update. Any help would be really appreciated. Thanks.

Answer 1

Please read this whole message before doing anything.
This procedure is a diagnostic test. It’s unlikely to solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.
The purpose of the test is to determine whether the problem is caused by third-party software that loads automatically at startup or login, by a peripheral device, or by corruption of certain system caches. 
Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards. Boot in safe mode and log in to the account with the problem. Note: If FileVault is enabled on some models, or if a firmware password is set, or if the boot volume is a software RAID, you can’t do this. Ask for further instructions.
Safe mode is much slower to boot and run than normal, and some things won’t work at all, including sound output and  Wi-Fi on certain iMacs. The next normal boot may also be somewhat slow.
The login screen appears even if you usually log in automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin. Test while in safe mode. Same problem? After testing, reboot as usual (i.e., not in safe mode) and verify that you still have the problem. Post the results of the test.