After quite a bit of fiddling, here's what I have done to open HTTPS on our Apache server. It was a bit complicated because we have so many virtual hosts.
First, follow all the info on this page. Then change your NameVirtualHost to only do virtual hosting on port 80:
NameVirtualHost *:80and change all the VirtualHost entries accordingly (adding ":80" at the end).
In the SSL virtual host, add the port specification:
VirtualHost *:443It should work straight away.