I am trying to use a WD Passport 1T external hard drive with my MacBook Pro but everytime I use the USB port it is recognized but shortly afterwards it ejects itelf from my system. How can I prevent this?
Once you resolve the ejection issue and the availability stabilizes, be sure to do a Repair Disk on the external drive with Disk Utility. Random forced dismounts like you are experiencing are great for corrupting the data on the drive.
I have the same problem with a Seagate FreeAgent GoFlex 2 TB drive using Firewire on my Mac Mini (late 2009). It worked perfectly for months on OS X 10.6. I have found no solution. Anyone have an answer?