Determined the error was in the syntax of the install msi. Corrected the syntax and all is well. Lesson learned . . . ALWAYS do careful scrutiny of information provided in requests and double check.
Thanks for the replies.
Running as system is not good because the install needs to update current user information. Running as current user encounters issues with reading Bas.cab not authorized. The action completes successfully but the error appears in the log that is being generated from the msi execution.
I agree with @jgstew, when troubleshooting, the more information, the better.
In general, one thing to watch for with running under current user credentials, is that unless the logged-on user is an Administrator, they won’t be able to read the files under \Program Files (x86)\BigFix Enterprise\__BESData\sitename\__Download.
Additionally, if you move the file from that path, it still retains the original permissions (allowing only Administrators and SYSTEM), due to the way NTFS handles move operations. If you copy to a new path, the new file gets new permissions based on the new target folder.
…which of course still doesn’t help you in the case of a software installation, if the user doesn’t have administrator rights needed to run the installation. But copying the file to a new location might at least get as far as being able to start the installer and allow the installer to prompt the user for UAC elevation.
If @JasonWalker has the cause of the issue, which it definitely seems like he has part of the issue, you can change the permissions on a folder and all of its contents with cacls / icacls: