I just got a new external drive yesterday, so I started copying across about 140GB of stuff to it and left the house. Six hours later I came home to discover the Finder had crashed and repeated relaunches did nothing, so I held down the power button on the Mac to restart it. At the time, the "Copying..." window was still present but was frozen with not much more progress showing than when I'd left the house. It didn't sound like there was any disk activity going on.

Now the new drive doesn't show up - won't mount, doesn't show up in disk utility in any way. Is it screwed?

What type of connection does the drive use?
eg: firewire/usb2

Does the drive power up and spin?

I have this issue with changing a drive from one mac to another.

I shutdown the second mac connection the drive which normally doesn't mount and restart and it just works.

If you have disk warrior try running it as it may see the external drive and fix any directory issues that may have happened.

Don't buy crap drives. Problem solved.

That reminds me what brand of drive is it?

USB2. Drive does power up and spin, but the Mac doesn't see it. Nor does DiskWarrior.

It's a Seagate (I think) in a Cooler Master enclosure.

Very helpful. You win at forums.

You could try to isolate the problem to the:

data
OS
USB port
USB cable
casing
hard disk.

Usually involves trying another computer/port/cable/casing etc.

And then depending on which one is defective, decide on whether you want to replace it.

If it's not the hard disk, then you could get the data off it, by replacing/bypassing the defective thingy.

If it's new, and not working on multiple computers, then I suppose it would be replaceable under warranty.

If the drive is powering up, it sounds like the enclosure is the failed part. Do you have a spare to try?

I actually bought two yesterday, one for my dad and one for myself. Heading over to his place now to check my enclosure and drive with his USB cable and Mac. If that still fails I'll swap out the drives and see which one is bad, the drive or the enclosure.

Thanks for the help

You did format it to HFS+ didn't you?

also try different cable/s and port on the mac this sometimes can also help.

It is starting to sound more like the case being the issue.

Eliminated these. Swapping out the drives next.

Yep.

It's the enclosure. Which is a surprise, because the enclosure (CoolerMaster Xcraft) appears to have a better reputation than the drive (Maxtor, not Seagate as I previously thought).

Now to try and get MSY to exchange it.

Thanks for the help guys.