Thank you for the lead!
I've found another forum that addresses the same issue. Reportedly, downgrading to 6.3.6 resolves the problem, though you have to contact Carbonite customer support to get the installer, though.
I was just on with Carbonite support to get that ball rolling. They uninstalled Carbonite (6.4.0) and upon restarting I was able to interact with .zip files without issue.
Next step is to get a call back from their senior escalation team and see about getting 6.3.6 (presumably) to get my back up process moving again.