Note:
If you visit your Web site using Internet Explorer on Windows XP, and suffer trouble like "untrusted root certificate",
get the root certificate update package from Microsoft WindowsUpdate page
"http://www.download.windowsupdate.com/msdownload/update/v3/static/trustedr/en/rootsupd.exe".
This package, when invoked, does not open any window, but updates root certificate store in the visitors' PC.