Re: Desktop Manager and Vista
First, make sure you're connecting your USB cord directly to the pc - no USB hub.
Vista was notorious for losing connectivity to peripherals like phones. You can try a different USB port on the pc. Best to do this while Desktop Manager is running. Another trick is to connect the BlackBerry, start Desktop Manager, and then do a battery pull on the BlackBerry while connected.
Finally, perhaps try another version of Desktop Manager.