Problems installing NW50Sp6A

I have downloaded SP6A for Netware 5.0 and need to install it in attempt to resolve issues with our tape backup. When I attempt to expand the file to NOVSP6A folder on my SYS volume, I get the following message: Verifying ARJ-SECURITY envelope andthe process hangs. I need to get this installed before I can proceed with troubleshooting the backup hangs. Any advice?