Some feedback.

I got it working.

I had to export it as a SHA1 only PFX file for use on Win XP.
With my previous certificate it had both SHA1 & SHA2 exported and I could
use the same PFX file in Win XP and Win 10.

I now have a PXF with only SHA1 in for Win XP and another PFX file with SHA1
& SHA2 for Win 10.

Maybe the new certificates are generated in a different way than the old
cetificates.
Got it working so I am all good.

Regards

Johan de Klerk