This software is required to be UN-installed before installing any current Receiver 4.x version.
It should be a default step in the Receiver installation package, done before installing Receiver 4.x.
Lots of registry and folder crap to clean out, I don't know if Citrix offers a cleaner-upper app or not.
We've mostly cleaned out ours but I think this will be useful to many people.
Thank you, Tom