This error only occurs when trying to print with my code.
I can launch Excel as an admin user and print manually, with three printers (including PDFCreator) available in the Print dialogue-box.
It seems to me that the printers are just not visible to the SYSTEM user, but I have no idea how to verify or fix this.
What can I do about it?
Several bits of code follow. I've removed some error handling and other things for brevity.
The following code starts PDFCreator: