By default, Powershell is configured to not allow scripts to execute.  To allow scripts to execute, the Set-ExecutionPolicy cmdlet can be used.  Run Powershell as administrator.  At the Powershell prompt type set-executionpolicy remotesigned.  This will set the policy for all users by default.  On a 64bit OS, set-executionpolicy must be run for 32bit and 64bit powershell separately.