Apologies for your problem being overlooked.
Kon might be able to offer a better answer when he comes online, but I think this could possibly be a .NET Framework issue as the updater relies on .NET Framework 4 and looking up that specific error, it is often associated with .NET problems.
Anyway, please try installing .NET Framework 4
, restarting your computer then re-running the updater.
If this does not work, let us know and we will try to find a better solution for you.