Hi BillTweedy:
You mentioned in your thread 
There is a problem with this website's security certificate that your antivirus is provided by British Telecom.
Is your McAfee software the British Telecom-branded version of McAfee named 
BT Virus Protect that is described in the support article 
What is BT Virus Protect and how do I get it? If so, see the section titled 
Why am I having problems adding BT Virus Protect to more computers in that support article.  Is it possible you used up all your available installation seats for BT Virus Protect before you replaced your hard drive and reinstalled Vista and now need to free up an installation seat?
The BT Virus Protect system requirements <
here> confirm this antivirus is compatible with Win XP SP3 and higher.  If you're sure you've performed your clean reinstall of Vista SP2 correctly (and updated your hardware drivers like your 
network card, graphics card, etc.) and still can't find an answer in this forum you might want to post about your BT Virus Protect installation problem in the 
BT support community.
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32-bit Vista Home Premium SP2 * Firefox ESR v52.9.0 * Malwarebytes Premium v3.5.1-1.0.365
HP Pavilion dv6835ca, Intel Core2Duo T5550 @ 1.83 GHz, 3 GB RAM, 250 GB SATA HDD, NVIDIA GeForce 8400M GS