Moved from http://blogs.msdn.com/vijgang
Applies to SharePoint 2007
While running content deployment import job on destination farm, you get the following warning message and the import job completes successfully.
This message would appear when trying to import a View or a Form template document.
Progress: Importing File Documents/Forms/template.doc.
Warning: User or group 5 cannot be resolved.
This warning message can be ignored. What this really means is that the 'Modified By' property of the imported item (usually a View or Form on which the error was thrown) is changed to the account of the user importing the content.
This means that if a specific template document say “/Forms/template.doc” is modified by a user 'User A' in the source and exported, then while importing in destination farm, the running import job will set the “Modified By” property of the imported item with the account of the user that is running the import job on the destination farm. Note though that the documents created using this template are not affected.