This can occur when a piece of software that NodeXL needs has previously been uninstalled. Due to a bug in that software's uninstaller, NodeXL is unable to reinstall the software, and you get the message you're seeing. (For reference, the problem
is described at
Unfortunately, the fix involves editing the Windows registry. If you are comfortable editing the registry, or you can dump this task onto someone who is, the fix is described in the above reference. I'll summarize the steps here:
1. Open RegEdit.
2. If you have a 64-bit version of Windows (which is what most recent computers have), navigate to the "HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\vsto runtime Setup\v9.0.21022" key. If you have a 32-bit version of windows, navigate
to "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\vsto runtime Setup\v9.0.21022" instead.
3. Change the key's "Install" value from 1 to 0.
4. Close RegeEdit.
5. Run NodeXL's Setup.exe program again.