I get this occasionally as well.  Short of rebooting one or both computers I can't ever remember what process works best.  I've tried unloading Multiplicity from the slave machine (it's crashed on the master) and reloading it on both but not even that works.  Wish someone from Support would chime in here.  Are there log files we can look at or submit?

If your problem is becoming more frequent and all your settings are the same and you still have the same version of Multiplicity installed then the odds are something network level is starting to fail.  Multiplicity keeps the same connections open for a prolonged period of time and is more likely to show up issues due to this.

A connection drop means just that, the connection has been dropped.  This could happen with multiple machines all sharing the same secondary, it could also happen if the computer is using almost all the cpu available (or network resources) and thus cannot reply to the are you alive queries which are sent every 6 seconds or so.  From the sounds of it if it delays 10 seconds that sounds very much like a 6 second are you alive followed by a 4 second timeout.  There should be a message on the popup saying why the connection was lost.

As IslandDog says please do contact support so they can further diagnose though.