I just moved house, and of course the first thing to do is plug in the media pc running MediaPortal, so that my shows will record. But as you would expect, change brings problems. It doesn't start. The pc boots, everything looks ok, but the TV-Server doesn't seem to be running. When I tried to launch the TV-Server Configuration, pops up an awesome dialog with a stacktrace in it:

Exception: System.NullReferenceException: Object reference not set to an instance of an object.
Server stack trace: 
void TvService.TVController.get_Cards()
void System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs)
void System.Runtime.Remoting.Messaging.StackBuilderSink.PrivateProcessMessage(RuntimeMethodHandle md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs)
void System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage msg, Int32 methodPtr, Boolean fExecuteInContext)
Exception rethrown at [0]: 
void System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
void System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
void TvControl.IController.get_Cards()
void SetupTv.Startup.Main(String[] arguments)

I have no idea what is wrong at this point. Has my card been damaged in transit? Is there some rogue signal on the satellite cable that is causing issues with the driver? Who knows.

At this stage, I have tried without the aerial, and it still has the same error, tried restarting, ensuring there was enough memory and hard drive space. The front-end software runs fine so it's only the TV-Service that is the issue. I didn't have a network cable plugged in, and windows was in a state of no network connection, as apposed to no internet access or connected.

I casually say to my Wife, while explaining the issue, "The Internet isn't connected, but that shouldn't make any difference." Her reply was "are you sure the internet isn't the problem?". Genius. I remember back to when I had wireless/wired network bridging a while back to pass through connection to my Xbox. The networking would die if the wired network had no signal, which happened whenever the Xbox was off, even though the internet was from the wireless.

So after much Google searching, and not seeing anything obvious to help my cause, I decided to try plugging in a powered network switch with a patch cable. this gave me a live signal in the cable, but doesn't provide a 'network' as such. But sure enough, as soon as I has that plugged in, everything came right. No network connected, no internet, not even DHCP resolution, but the fact there was a switch at the other end of the cable was enough, and all is well.

Today, after solving the issue, I found this post that explains it has to do with the TV-Server binding to the IP address, (which windows created for me after not locating a DHCP server) and also suggests a loop-back interface driver that can be used to fix the issue through software means.

Luckily for me this is only a temporary issue, and my powered switch workaround will do the trick until I get Broadband connected and my flat network wired up again.

TL;DR If you get the NullReferenceException, and messages that say no cards available, make sure your network at least resolves an IP address, even if it is just a loop-back or an Automatic Private IP Address.