If you're having hitching problems, can't connect to the NWI servers, or general problems with EAC, I suggest checking to see if you're opted into the Steam Client beta program. I was, and was having these issues - opting out and going to the main branch of Steam Client fixed all of these problems. I don't know if this problem is caused by the Steam Client beta interacting with EAC or if just refreshing the Steam Client files is what did it.

If you don't know how to leave the beta, here's how: in the Steam program, go Steam -> Settings. In the Account section, there should be a section for Beta Participation. Hit "Change" and then select "NONE - Opt out of all beta programs."