[Juser] "Invalid CA certificate" for jabber.org?

[Roland Bluethgen]

Hi there!

I'm trying to connect to the jabber.org server using the Jabber client 
Psi on Windows 2000, and of course using SSL. However, Psi keeps telling me
"The jabber.org certificate failed the authenticity test. Reason: 
Invalid CA certificate."

I don't know what the reason for this is. It appears to me that I need a 
root certificate for Commodo Limited, which is the issuer of the 
jabber.org cert according to what Psi tells me. So I tried to find that 
cert and found http://www.comodogroup.com/repository/ . However, 
installing the three certs at the bottom of that page didn't solve the 
problem. (I know that Psi requires a special format for the certs which 
was easy to provide.)

So, either I still don't have the correct root cert, or there's a 
completely different reason for the authenticity failure.
Can anyone point me in the right direction?

So long