A similar problem, I mistakenly put my old Logitech Bluetooth dongle in a usb port (I no longer have any bluetooth devices). It automatically ran the Logitech Bluetooth Connection Assistant and of course never completes since it can not find any devices. Now every start up this stupid Bluetooth Connection Assistant pops up and sits there, I have tried every possible way to get rid of it and nothing works, msconfig, services, looked in the start menu, it is acting almost like a virus or malware now. Where have they buried the executing file? I even tried looking in a logitech .ini file and didn't see any clues as to where it is being called from.
I may post this in a separate thread but I thought I would give your thread a boost since it seems related. I will eventually try the Logitech forums as well. Thanks.