Progress report error

Our clients run through Citrix, and sometimes, when trying to print a Progress report, like Shop Load, the user will get an Unhandled Exception error with the message:
"Settings to access printer 'Default printer is not set' are not valid"
(not a typo, that's the actual message)

The user has a default printer, so I am unsure what this could be.
Has anyone on Citrix experienced this message?

Thanks in advance.