.NET programs don't run at logon screen - windows 7

I'm using Windows 7 Pro (开发者_StackOverflow32bit) and have .NET 3.5 and 4 installed...

I have written a .NET screensaver and have enabled it to run on the Windows logon screen.

My problem is that it errors:

.NET framework initialisation error

BUT when I'm logged in the screensaver works...

So it isn't a faulty installation of the .NET framework, or else it wouldn't work fullstop.

Any ideas?

That is not possible on login screen. The core services needed to be able to run a windows program(.Net or not) have not yet been loaded/initialized.

Unless your trying to develop a program outside of windows' jurisdiction (such as bootable, console programs)