Thanks Brazil.
From the searches I performed looking for a fix to this, I agree IconX has got some problems currently. 1.99n fixes some of the issues I found posted, but not this particular one.
I'm still working though, I just turn IconX off (Oh the horror of the standard Icon!

), or revert to 1.99h that I have archived and I'm golden. I haven't found a compelling reason to use the latest build yet, but I'll keep trying.
As I said it's weird this is happening on one computer and not another so if you have any ideas what I need to install/uninstall, I'm all ears.