"Paul" <Paul@newsgroup> wrote in message news
> "Ildhund" wrote:
>> Is your computer clock accurate, date and time?
> Thanks for the response Noel,
> I checked with all servers available in the Date and Time settings, and various other sources, and am confident that the computer clock / date and time is accurate.
> I also tried one of the above accounts on a different machine (Windows XP (x86) Service Pack 3, my machine is Windows 7 (x64)) and had the same error message.
OK. I don't pretend to know the first thing about certification, but if your computer date is awry, a certificate which hasn't yet expired might look as if it has and you would probably get the error you describe. So that's a first troubleshooting step.
Root certificates (stored on your computer) are usually updated automatically as required; i.e. Windows calls home to check whether a certificate is still valid. This process can be disabled through Group Policy, though, and may have been if, say, the machines you're using have been configured by some institutional IT tech (OU?). So that's another thing to check. In XP, this would involve
* Start > Run > gpedit.msc
* Computer Configuration > Administrative Templates > System > Internet Communication Management > Internet Communication settings.
Turn off Automatic Root Certificates Update would be Enabled if that's your problem. I've no idea whether there's anything similar in W7.
And the last thing to check: Windows Update regularly offers an optional Root Certificates Update. If you have Automatic Updates configured, you won't see it - only by visiting the WU site. The last was in November 2009, I think.
That should keep you busy for a bit. You could try googling windows root certificate update to get lots of reading material.