I am not having any of this problem. For us the eRx do not generate nearly the number of call backs that the faxed Rx did.
As I having been using AC now since 04-2009 in general I would say that most of the time that I was having a problem that wasn't been by lots of users it was a "local" problem in my system and not AC.
If some of the Rx go through and not others I think an unreliable internet access sounds pretty plausible.
