Hi, this is from another person with the same problem, and this was the response:
From your Safari menu bar click Safari / Preferences then select the Autofill tab.
Make sure *user names and passwords* is selected.
Now click the Edit button next to: *Other forms*. Delete all the url's for the sites you have problems logging in to.
Now select the Security tab. Click: *Show Cookies* Delete all cookies related to the sites you are having problems accessing.
Quit Safari. (Command + Q)
Open Keychain Access (Applications/Utilities). Select Passwords on the left.
Delete all the keychains for the sites you have problems logging into.
Relaunch Safari. Navigate to a site you normally login to. Type in your *user name and password*, click Yes when prompted. A new keychain will be created for that site.