Us.data.toolbar.yahoo.com:443 uses an invalid security certificate.

Hello
I have been experiencing an error on my screen for the last few days about connection security.
I can't understand what does this error means and how can I fix it up.
I have attached the screenshot of the error below:

The error states:
Secure connection failed
Us.data.toolbar.yahoo.com:443 uses an invalid security certificate.
The certificate will not be valid until 6/23/2010 7:21 PM.
(Error code: sec_error_expired_certificate)
This could be a problem with the server’s configuration or it could be someone trying to impersonate the server. If you have connected to this server successfully in the past the error may be temporary and you can try again later. There are no changes that I have made to my system recently. I only uninstalled some of my applications, and that’s it.
Can anyone tell me the reason for this error please and how can it be fixed.
Waiting for your replies.
Thanks,
Regards.
