MacBook Pro won't recognize ext HD

Mac OS X 10.6.8 - My Seagate 500Gig ext hard drive usb bus is not longer being recognized in Finder. I can see it in Utility and in "About Mac" - "more info", but not Finder. I've 'Verified' it and 'repaired' it, but there's nothing wrong with the HD. Other usb peripherals are working fine.

I read a thread earlier (now can't find it) and it seems issues from as far back as mid 2010 were reported. My cache is clear, I have plenty of power, new cable, checked both ports.

Any ideas?

There have been problems with Seagate drives in general. Apple recently recalled iMacs which had the Seagate 1 TB drive installed. If the drive is still under warranty, contact Seagate and get an RMA and have them send you a replacement.