Did you run the install as 'root'?
Make sure you only try to install the version from the XI tarball or the exchange. Newer, vanilla versions from the nagvis site will not work out of the box and cause all sorts of issues.
Former Nagios employee
"It is turtles. All. The. Way. Down. . . .and maybe an elephant or two."
VI VI VI - The editor of the Beast!
Come to the Dark Side.
I just found this post while having issues with the NagViz install. Turns out the install script was failing after downloading version 1.5.9 of NagViz. Here is what the failure looked like:
tar (child): nagvis-1.5.9.tar.gz: Cannot open: No such file or directory
tar (child): Error is not recoverable: exiting now
tar: Child returned status 2
tar: Error is not recoverable: exiting now
It calls it "download" after it downloads it and then complains that "nagvis-1.5.9.tar.gz" does not exist. I solved it by renaming "download" to "nagvis-1.5.9.tar.gz" and rerunning the shell script. It installed without issues. 1.5.9 is way old though, wish someone had the time to update the shell script to work with a newer version of NagViz.