When loading an InfoPath form from a Sharepoint document library, you may be presented with a policy error message indicating that (Internet) forms with managed code cannot be loaded.

This can be a pain in the neck while developing, but can be circumvented by making the following registry change;

HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\InfoPath\Security:RunManagedCodeFromInternet(DWORD) = 1