SQL Agent Powershell Job Failing with Non-Admin Proxy
Solution 1:
Check your execution policy within Powershell; sounds like it might be failing because the default setting is "Restricted", which only allows Powershell to run as an interactive shell, and does not execute scripts at all. See the following link for details:
http://technet.microsoft.com/en-us/library/ee176961.aspx
EDIT: Just realized the above link only describes syntax for "Set-ExecutionPolicy"; this link should provide some additional context also:
http://technet.microsoft.com/en-us/library/ee176949.aspx