When I attempt to download a file from Hotmail I get a Certificate Error. This is unrelated to I.E (I have just upgrated to I.E 10) as it occurs in Firefox and Google Chrome too.

This problem also occurs when I try and download an email attachment that I have downloaded before with no problems.

I have forwarded a Hotmail message to my Gmail account and I can download the attachments fine. Therefore I assume the problem is purely a Hotmail (Outlook) issue.

This problem has occurred since yesterday (27th August 2013).