Search Exporter is unable to export to a PST larger than 2GB in size.
This is a limitation of Outlook 2002 and earlier. These versions only support ANSI PST files up to a maximum size of 2GB.
To allow the creation of a PST larger than 2GB, install Outlook 2003 or later on the workstation where Search Exporter is installed. These versions support Unicode PST files with a default limit of 20GB.
If Outlook 2003 or higher is already installed and a 2GB limit is still imposed ensure that the PST Output Format in Search Exporter is set to "Office Outlook" not "Outlook 97-2002".
To allow PST files larger than 20GB in Outlook 2003 or higher please see this Microsoft KB article: http://support.microsoft.com/kb/832925/