Just posting this blog tonight hoping it might save someone else a bunch of time. For call recording on Skype, I use a program called Pamela. Lately, when I'd first installed it, it would work fine. Later, however, it would come up and say:
"Another application (Pamela.exe) is attempting to access Skype, but we are unable to respond".
You just have to love these sorts of messages that don't give you the slightest clue about what the problem is.
While I saw the problem with Pamela, it can happen with any Skype add-in. The problem actually is related to UAC. If Skype is running as non-admin (startup app in windows) and you launch the other app as admin, you'll get this error message. Amazingly, running the add-in without admin privileges makes it work. The irony is that I was trying it as admin because I thought that would make sure it works.
Hope that helps someone else as I certainly wasted endless hours trying to work out what was wrong. And a big raspberry to the Skype guys for the "useful" error message.