xenroll.dll error - Newbie

[bev]

Without going into all the dreary details of what I don't know etc, suffice it to say that our Server Certificate expired and I needed to renew it. After much muddling, we seem to have solved that problem (at least til next year). And we did it all in-house, not using an outside authority. But I used to be able to request a Client Authentication Certificate from my workstation, whereas now I get a message telling me that the enrollment control (xenroll) did not successfully download to my machine.

I can generate a Client Authentication Certificate from the IIS Server. We're running IIS 4, Microsoft Management Console V1.0, Microsoft Certificate Server (don't know version, probably V1.0)

Any idea what is causing this xenroll.dll error?
Bev