SBS server with IIS 6

Hi,

Just installed SBS on computer at the charity i run, set static ip with isp to point to my domain name etc, couldaccess the default web page on IIS for a short time which gave me access to the server remotely but after about an hour if i try and access again through IE7 remotely it tells me the website is unavaliable.
#
There is also a problem with the security certificate and am not sure if that may be the problem…

Please help

Cheers, Paul