I wresteled with this same problem all afternoon. The issue results from how the installshield package is configured. The installation spans across more than one CD; hence, all 6 folders, i.e. disk1..disk6 must reside on the target filesystem. A helpful link from installshield prompted me to remember that I had encountered this same issue before:

http://support.installshield.com/kb/...icleid=Q105582

Good luck to anyone else that encounters this thread.