I use Mac...So not a direct reflection...I have been doing running a few "tests" and I do seem to appear to not be able to connect to anything from dashboard even though it thinks there are available items....I find I can do this more often when I wake the machine back up when I come to my desk.
I have to restart DashBoard to get everything to come back up...Not sure this is happening to you or is it just the Media Manager but you could try the same thing I am going to test if you have more than 1 network device / connection on the computer.
I have more than 1 IP address and port running...I am now going to be trying to lock Dashboard (in preferences under Automatic Discovery) to a single Network Interface.
Also in the past I have seen media manager lose connection if extensive USB access takes place -- ie FTP of many files or if a show file load and save is taking place which limits the access to the USB..
#Carbonite