I don't have one to test, but from the sounds of the issue it is an issue with Win 8 not allowing the driver to initiate.
Which would make sense in the clean install assuming the driver was installed on Win7, and then updated to Win 8 you would not have the EFI boot to stop unsigned drivers initiating.
If this is correct, the methods here may help you
And the driver is from February 2013 on Xerox.com.
Does it currently work in other applications like Windows Fax and Scan ? If it is just in Paperport we could be troubleshooting the wrong thing entirely