I've installed LabVIEW 2013 on several PCs, and at least three time, I have received the message "Network Discovery Service 5.5 could not be installed". I (now) know how to "fix" this, and am posting this here in case someone else sees the same thing.
What I did was to abort the installation, reboot the PC (even if I had just booted it before the installation), and tried again. This worked three times (including just now) ...
Bob Schor
P.S. -- I have no idea why I get this error in the first place. I was trying to install LabVIEW 2013 "by itself" from a 4-DVD distribution kit, but the first time I encountered this error, I was installing from the LabVIEW 2013 Download from NI.