SYMPTOMS
When installing the Sperry Software add-in, you receive the following error message:

          Error 1606: Could not access network location

CAUSE
N/A

RESOLUTION
The first thing is to copy the installer MSI file to your local drive then try installing the add-in from there.  If this doesn't work, or you already saved it to your local drive and ran the MSI from there, then there are some registry changes which may need to be made. 

If you are not sure what you're doing (see this Microsoft article on the registry).  Then look at this article that explains how to check user folders.