hmm that doesn't sound right! Certainly the core (and MDs) will connect periodically either to confirm the share is still online or for UpdateMedia to resync. Then you will see in your Security log a bunch of events - there are several different events logged relating to each individual authentication, so don't double count them.
This will likely happen every 5 seconds or so. However, UpdateMedia should only be triggered 2 mins after the previous one completed. In other words it sleeps for 2 mins before starting again. But that shouldn't really be generating authentication attempts (except when it first starts and connects)... instead you should see a session appear in Computer Management -> Shared Folders -> sessions...
I have seen UpdateMedia get into a spin and pretty much scan continuously 24/7 but as I say, that shouldn't be generating authentication attemps... one point is, have you set a username/password in the LMCE definition for that share? Perhaps you should do that and give that username full access to the share.