I'm getting a frequent (but not 100%) problem when using FT mobile where my browser says "There are problems with the security certificate for this site" and offers "Go back"/"View certificate"/Continue". On viewing the certificate it either says it's out of date (some adobe site - I didn't copy the name) or that it's not from a trusted authority ("*.adsafeprotected.com" issued by "COMODO RSA Domain Validation Secure Service CA") . In the first case, the certificate had expired a few days or weeks ago; in the latter case, the certificate is still valid (issued in August, good until 2020).