In my case, the command line build was causing -6003 error while attempting to stream "0x0427.ini" file into setup.exe. The reason was that the file was missing in my IS2008 installation (in both IS2008 IDE as well as in IS2008 Standalone Build). The default installation of IS2008 (IDE+SAB) didn't have support for Lithuanian language installed; but my project was supporting Lithuanian, causing the build error.

The workaround was to copy the English language equivalent of the missing file (i.e. 0x0409.ini) into "0x0427.ini" file under both IDE and SAB installations "Redist" and "Support" folders respectively. A better solution would have been installing Lithuanian language support in target IS2008 setup.