reboot both devices, and I mean pull the plug on both wait 30 seconds, reboot. will cure it for a while, make sure the devices are getting plenty of air!!!
edit: I was scared the first few times this happened, thought 2 TB's worth of data was lost. since then I have put the Rosewill enclosure on it's side so I can keep an eye on the screen, so it does not get full of dust. indoor dryers and a few blocks from freeways does wonders as to how often you have to vacuum with a good hepa filter
I read many sites before doing the external drive thingy and it seems the 3 TeraByte models have a lot of THERMAL issues and even data loss, and the old days when drive makers made tall drives with lots of platters are sadly gone. so now they rely on the latest inventions at IBM labs and areal densities. in other words I stay away from them even for computers that also have issues to this day with "modern" BIOS's