For a single users PC the Excel Add-in was not working.
It was definitely a corruption in their install, but a reinstall did nothing to fix it.
A lot of files are left over after an uninstall, including all the previous credentials.
The only way to fix that is to clean the registry. I have even included an attachment here with the registry deletion scrip you can simply copy/paste. I wish I had seen a post like this - it would have saved me hours of procmon tracing and research.
