hello heathdj1, first please make sure that your system clock is set to the correct date, time and timezone. in case this doesn't help or is already configured correctly, a possible solution depends on different factors:

• what is the error code shown under technical details on the error page?

in case the error code equals sec_error_unknown_issuer, please attempt to add an exception on the bottom of the error page & inspect the certificate (see the screenshot attached for instructions):

• which issuer information does the certificate contain?

thank you!

"This Connection is Untrusted" error message appears - What to do

It's a problem with the current certificate Microsoft is using on the site, it is not valid for https://www.hotmail.co.uk, use https://hotmail.co.uk instead:

Technical Details www.hotmail.co.uk uses an invalid security certificate. The certificate is only valid for the following names: mail.live.com, m.mail.live.com, contacts.live.com, hotmail.co.jp, hotmail.co.uk, hotmail.com, hotmail.live.com, hotmail.msn.com, people.live.com, www.hotmail.com, www.hotmail.msn.com, www.mail.live.com, home.live.com, www.live.com, dvt.mail.live.com, dub109.afx.ms, dub109.mail.live.com, origin.dub109.mail.live.com, dub110.afx.ms, dub110.mail.live.com, origin.dub110.mail.live.com, dub111.afx.ms, dub111.mail.live.com, origin.dub111.mail.live.com...

Did you try to omit the www. prefix and use https://hotmail.co.uk ?

Is this with a bookmark or with a link on a web page?