website security certificate problem

Hi, something strange is happening with my pc on some sites.
When i go onto ebay or yahoo i get a message saying that the site's security certificate has expired and i shouldn't go into the site.
This has been happening for about a month now and i think it must be something to do with my pc because these are well known sites that would not have a problem like that long term. Even on this site now, i have a red cross on the phishing filter, and a red circle with a red line through it on privacy report.
I'm using IE7 and xp home, with all the updates.

Can anyone advise me on this please, i'm a bit worried that someone has hacked my pc.

many thanks

Sounds like your clock is slow.

thanks train, thats sorted the certificate prob.

but i've still got the red circle on privacy. any ideas on that?

The red circle just means it is a Restricted Site. That is not a problem.