Attempted to read or write protected memory

I had the same problem after upgrading from .NET 4.5 to .NET 4.5.1. What fixed it for me was running this command:

netsh winsock reset

I had the same problem. 2.0 worked fine. after installing up to 3.5 sp1, application gets Access Violation.

installed http://support.microsoft.com/kb/971030 and my problem is solved, even though I am not using LCG.

Microsoft also released a hotfix (July 2nd, 2007) to prevent the error "Attempted to read or write protected memory" that has been plaguing the .NET 2.0 platform for some time now. Look at http://support.microsoft.com/kb/923028 - not sure if it applies to you, but thought you might like to check it out.