Scratch

a primitive has failed:
NetNameResolver class(Object)>>error:
NetNameResolver class(Object)>>primitiveFailed
NetNameResolver class>>primNameResolverStatus
NetNameResolver class>>resolverStatus
NetNameResolver class>>initializeNetworkIfFail:
Socket class>>initializeNetwork
PowerpackWebServer(ScratchServer)>>startHosting
ScratchFrameMorph>>startServer
[] in UndefinedObject>>DoIt
ScratchFrameMorph class(Behavior)>>allInstancesDo:

I have had this error several times before, and it is annoying me at the moment. What is causing it?
I have all the required dlls in the folder so the primitive must be there.