He says the problem began one night after working on some data from his work.
Did he use some sort of remote access tool to connnect to a PC or server at work? Something like a VPN for example.
I'm wondering if the PC still thinks secure connections should go via this route which is now closed to it.
edit:
Actually re reading that i'm wondering if it's now too late and i'm not making sense... can https be set to use another DNS to http?