Problems with certificate, not certified

[abrj]

I have Problems with certificate.
A year ago I installed xampp 2 on my Windows XP machine acting as an internal webserver.

Somehow, a year ago I managed to make a certificate using makecert.bat and somehow got it signed/trusted. When I accessed the webserver from other computers using Opera, IE 7 and so on I got a yellow “sign” up in the right corner of the urlfield of the browser, telling me that this certificate was trusted and so on.

Now my certificate ran out on date, so I ran makecert.bat again. But, now I can’t make it certified/signed. I get “errormessage” when accessing my secure site with external browsers, and when I look at the certificate it tells me the site is not secure, because the certificate isn't signed by any trusted companies.

Can anyone help me? Did I use openssl to make it certified? I don’t remember. I use Xampp on Windows XP