I followed this instruction:
http://calibre-ebook.com/user_manual...with-my-iphone
So when it doesn't connect, I went into the same screen again, clicked the "edit" button, edited the Server I added (using the above instructions), then save it again.
But just last night that did not work either.
So I went into Calibre's settings and STOPPED the content server (I have it on auto-start on program launch). When I then tried to re-start it, I got an error message without a message ... just a red sign.
So I clicked on "start" again, and whoop dee doo ... Stanza finds Calibre again.
Guess I need to send a screenshot to Kovid, maybe he knows what's up with my machine.