Users are not able to get the remote list viewer web part working on their sites: Either get a "404 error" or get a "Could Not find the specified site/list" error
Product & Version
KWizCom Discussion Board Standard Evaluation 1.x.xx for SharePoint 2007
KWizCom Discussion Board Evaluation 11.x.xx for SharePoint 2010
Try to check Alternate access mappings, also make sure that you use the same host header in web part configuration.