hi forum newbie here

I've been having an issue with my mac mini when networking to my win7 PC
ill start to transfer files from the mini to the pc but if the files are either large >1gig or lots of small ones the Share Dies... i can still see the pc but can't reconnect to the PC without rebooting both machines I've tried to reinit both networks by disable and restart them but all i can see on the Macs end for share is / .. they are connected via a gigabit (10/1000) switch the pc can still network to the other pcs on the switch but not the mac .... to sum it up ... its like the network card on the mini locks up.... is this a common problem ?