As I understand it this error means WU had a problem with the ssl connection back to MS and usually that's just a case of making sure the computer is on the right date, time etc.
However I have a computer throwing up that error with the correct date etc set. It can also browse https websites in IE (even microsoft.com) without any problems.
Over the weeks I've had several goes at fixing it and I'm afraid I can't list all the things I've tried because... I'm stupid.
The windows update troubleshoot thing from here https://support.microsoft.com/en-gb/ins ... bleshooter
doesn't find any problems.
I'm not noticing any certificate errors while visiting websites in IE.
EDIT: Forgot to add that MS Security Essentials is on this machine and that is still receiving updates. I assumed they came through windows update which confuses me even more.