None of this worked in my specific instance. What did was changing to a NetBIOS name from the FQDN.
Instead of:
\\server.domain.net\file.ps1
use:
\\server\file.ps1
Using the name bypasses the "automatically detect intranet network" config in IE.
See Option 1 in the blog here: http://setspn.blogspot.com/2011/05/running-powershell-scripts-from-unc.html