install.log says:
Could not run InstallationCheck in the Symantec Endpoint Protection package. launch path not accessible
This package is the same package I've used on a few other Macs, provided by the people who manage SEP for our organization. The only difference I'm aware of is, the others I've installed on were fresh installs of 10.7 updated to 10.7.5, and this MacBook is an existing 10.6.8 OS.
I saw the reference to "The Unarchiver", but aren't sure how to find out if this mac has it. I didn't see it in Applications, but don't know enough about Macs to query a package manager or whatnot to find out.