irq = new InterruptPort(irqPin, true, Port.ResistorMode.PullDown, Port.InterruptMode.InterruptEdgeLevelLow);

Which breaks on line:

if (loopMax <= 0) throw new Exception("Unable to Communicate to the Ethernet Controller.  Check the InterfaceProfile in your Adapter.Start()");

From the code:

/// <summary>
/// Starts up the driver and establishes a link
/// </summary>
public void Start()
{
byte i;


var loopMax = 100;  // about 10 seconds with a 100 ms sleep


// Wait for CLKRDY to become set.
// Bit 3 in ESTAT is an unimplemented bit.  If it reads out as '1' that
// means the part is in RESET or there is something wrong with the SPI 
// connection.  This loop makes sure that we can communicate with the 
// ENC28J60 before proceeding.
// 2.2 -- After a Power-on Reset, or the ENC28J60 is removed from Power-Down mode, the
//        CLKRDY bit must be polled before transmitting packets
do
{
i = ReadCommonReg(ESTAT);
loopMax--;
Thread.Sleep(100);
} while(((i & 0x08) != 0 || (~i & ESTAT_CLKRDY) != 0) && loopMax > 0);


            if (Adapter.VerboseDebugging) Debug.WriteLine("ESTAT: " + ReadCommonReg(ESTAT).ToString());


if (loopMax <= 0) throw new Exception("Unable to Communicate to the Ethernet Controller.  Check the InterfaceProfile in your Adapter.Start()");


            regCheckTimer = new Timer(new TimerCallback(CheckRegisters), null, checkDelay, checkDelay);
            watchdog = new Timer(new TimerCallback(WatchDogCheck), null, 10000, 3000);


Restart();
            //Init();
}

case InterfaceProfile.Netduino1:
                    // MOSI(D12), SCK(D13), MISO(D11), INT(D8), CS(D10) 
                    Start(MacAddress, name, SPI.SPI_module.SPI1, SecretLabs.NETMF.Hardware.Netduino.Pins.GPIO_PIN_D8, SecretLabs.NETMF.Hardware.Netduino.Pins.GPIO_PIN_D10);
                    break;

My interrupt method is as follows:

irq = new InterruptPort(irqPin, true, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeLevelLow);

I now get the error:

        /// <summary>
        /// Take care of a packet of DHCP stuff
        /// </summary>
        /// <param name="payload"></param>
        public static void HandlePacket(byte[] payload)
        {
            //Debug.WriteLine("Handling DHCP packet");
            
            // Check Transaction ID!
            if (transactionID == null || payload[46] != transactionID[0] || payload[47] != transactionID[1] || payload[48] != transactionID[2] || payload[49] != transactionID[3]) return;
            
            // To determine the type, we need to find the magic cookie, then find option 0x35h
            // 02 == Offer, 05 == ACK, 06 = NAK
            var options = ParseOptions(payload);


            //Debug.WriteLine("DHCP PKT");


            if (options.Contains("53"))
            {
                //Debug.WriteLine("Rec'd DHCP OFFER - 1");


                if (((byte[])(options["53"]))[0] == 0x02)  // Offer
                {
                    //Debug.WriteLine("Rec'd DHCP OFFER");


                    ushort ipHeaderLength = (ushort)((payload[14] & 0x0f) * 4);
                    PendingIpAddress = Utility.ExtractRangeFromArray(payload, ipHeaderLength + 38, 4);
                    if (options.Contains("54")) Adapter.Gateway = (byte[])options["54"];  // DHCP Server
                    if (options.Contains("6")) Adapter.DomainNameServer = Utility.ExtractRangeFromArray((byte[])options["6"], 0, 4); //DNS Server
                    if (options.Contains("6")) Adapter.DomainNameServer2 = Utility.ExtractRangeFromArray((byte[])options["6"], 4, 4); //Secondary DNS Server
                    if (options.Contains("1")) Adapter.SubnetMask = (byte[])options["1"];  // Subnet
                    if (options.Contains("3")) Adapter.Gateway = (byte[])options["3"];  // Router
                    if (options.Contains("58")) RenewTimer.Change((int)(((byte[])options["58"]).ToInt() * 1050), TwoHoursInMilliseconds); // Got a Renew time
                    if (options.Contains("51")) RenewTimer.Change((int)(((byte[])options["51"]).ToInt() * 750), TwoHoursInMilliseconds); // Got a Lease Time (I am using 750, so we renew after 75% of lease has been consumed)
                    Adapter.GatewayMac = Utility.ExtractRangeFromArray(payload, 6, 6);  // Initial gateway MAC.  Will get confirmed/updated by an ARP Probe


                    SendMessage(DHCP.Request);
                }
                else if (((byte[])options["53"])[0] == 0x05)  // ACK or Acknowledgement
                {
                    // Parse out the Gateway, DNS Servers, IP address, and apply set all the variables with it...


                    //Debug.WriteLine("Rec'd DHCP ACK");


                    if (options.Contains("54")) Adapter.Gateway = (byte[])options["54"];  // DHCP Server
                    if (options.Contains("6")) Adapter.DomainNameServer = Utility.ExtractRangeFromArray((byte[])options["6"], 0, 4); //DNS Server
                    if (options.Contains("6")) Adapter.DomainNameServer2 = Utility.ExtractRangeFromArray((byte[])options["6"], 4, 4); //Secondary DNS Server
                    if (options.Contains("1")) Adapter.SubnetMask = (byte[])options["1"];  // Subnet
                    if (options.Contains("3")) Adapter.Gateway = (byte[])options["3"];  // Router
                    if (options.Contains("58")) RenewTimer.Change((int)(((byte[])options["58"]).ToInt() * 1050), TwoHoursInMilliseconds);  // Got a Renew time
                    if (options.Contains("51")) RenewTimer.Change((int)(((byte[])options["51"]).ToInt() * 750), TwoHoursInMilliseconds);  // Got a Lease Time (I am using 750, so we renew after 75% of lease has been consumed)
                    Adapter.GatewayMac = Utility.ExtractRangeFromArray(payload, 6, 6);  // Initial gateway MAC.  Will get confirmed/updated by an ARP Probe


                    transactionID = null;
                    Adapter.AreRenewing = false;
                    Adapter.IPAddress = PendingIpAddress ?? Adapter.IPAddress;


                    Adapter.startupHold.Set();  // This will release the Adapter.Start() Method!  (if waiting)


                    Debug.WriteLine("DHCP SUCCESS!  We have an IP Address - " + Adapter.IPAddress.ToAddress() + "; DNS Server: " + Adapter.DomainNameServer.ToAddress() + "; Gateway: " + Adapter.Gateway.ToAddress());


                    ARP.SendARP_Probe(Adapter.Gateway);  // Confirm Gateway MAC address
                }
                else if (((byte[])options["53"])[0] == 0x06)  // NACK or Not Acknowledged!
                {
                    Debug.WriteLine("DHCP N-ACK");
                    transactionID = null;
                    Adapter.AreRenewing = false;


                    // We have failed to get an IP address for some reason...!
                    Adapter.IPAddress = null;
                    Adapter.Gateway = null; 
                    Adapter.GatewayMac = null;
                }
            }
        }