Add-Type -Path "WinSCPnet.dll"
This now returns the error:
Error: Could not load file or assembly 'file:///C:\APUDATA\WinSCPnet.dll' or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515)
I noticed that the upgrade to PowerShell v4 also required installing .NET Framework 4.5. I saw another post where you said you can't work with .NET 4.0, so is 4.5 also a problem? If so do you have a workaround?