I am attemping to use NetUseAdd to add a share that is needed by an application. My code looks like this.

[DllImport("NetApi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
internal static extern uint NetUseAdd(
     string UncServerName,
     uint Level,
     IntPtr Buf,
     out uint ParmError);

...

USE_INFO_2 info = new USE_INFO_2();
info.ui2_local = null;
info.ui2_asg_type = 0xFFFFFFFF;
info.ui2_remote = remoteUNC;
info.ui2_username = username;
info.ui2_password = Marshal.StringToHGlobalAuto(password);
info.ui2_domainname = domainName;

IntPtr buf = Marshal.AllocHGlobal(Marshal.SizeOf(info));

try
{
    Marshal.StructureToPtr(info, buf, true);

    uint paramErrorIndex;
    uint returnCode = NetUseAdd(null, 2, buf, out paramErrorIndex);

    if (returnCode != 0)
    {
        throw new Win32Exception((int)returnCode);
    }
}
finally
{
    Marshal.FreeHGlobal(buf);
}

This works fine on our server 2003 boxes. But in attempting to move over to Server 2008 and IIS7 this doesnt work any more. Through liberal logging i have found that it hangs on the line Marshal.StructureToPtr(info, buf, true);

I have absolutely no idea why this is can anyone shed any light on it for tell me where i might look for more information?