Hi! I bought a new USB3 drive for Time Machine and I'm using the old one for data. It is divided in two 256GB partitions. One always works fine, but the other sometimes prevent me from writing to it! If I verify it with DiskUtility, says nothing is wrong BUT afterwards it starts working as it should (allowing writing to it)! It happened a couple of times, without apparent reason. What is happening and how can avoid this? It's more annoying and time wasting than anything, but I'd like to solve it. Mac Mini with Mountain Lion, 8GB system RAM.