External HD periodically closing

I'm running OSX 10.7.3 Lion on 27in Cinema Display with 8 GB of memory, Processor 3.1 GH Intel Core i5.

Already have a WD 2 TB HD that I use for Time Machine Backups. Attached another WD 3 TB HD for archiving Home movies. Periodically, it shuts down (sometimes a few minutes, sometimes 15 or so) and a screen alert comes on: "! The disk was not ejected properly. If possible, always eject a disk before unplugging it or turning it off. (Then in less bold type) To eject a disk, select it in the Finder and choose File > Eject. The next time you connect the disk, Mac OS X will attempt to repair any damage to the information on the disk." Of course, I didn't do any of those things.

Sometimes, within seconds or a few minutes, the HD icon will appear back on my desktop as if nothing happened.

I previously had a 2 TB HD that preceded my current one, and thinking that it was a bad HD, I replaced it with a new WD 3 TB HD. Same results.

What gives?

Most likely this has to do with the Energy Saver preferences. Try unchecking the option to Put the hard disk(s) to sleep when possible and see if that solves it.

Ok. Changed System Preferences to "Never Sleep" for Hard drive

I do have MacKeeper. How do I uninstall it?

cheesehead fred said:

I do have MacKeeper. How do I uninstall it?

Click to expand...

Via the instructions I linked to in my signature.

This could also be a symptom of the WD drive dropping off of the bus. Check the following and see if any/all of these solve the problem:

1. Check the data (usb/firewire) cable coming to the drive. a faulty cable can cause this problem.
2. If this drive is USB-based make sure it has its own power cord and isn't relying entirely on the bus for power.
3. If #2 isn't an option or the drive is using two USB ports for power try plugging it into a hub that has its own electrical power.