I was having the same problem copying my roms over to the f drive. It would get to the S's and stop and tried everything i could even deleted some games off my harddrive even though i had 8 gigs available. Finally i used Xcommander and copied the individual zips over like 60 at a time and that worked. There is obviously some kind of bug when copying a large amount of files. Hopefully someone will look into it. By the way i was doing this for the MAME roms.