Mac peripherals forum: External hard drive not readable

Dear All

I use an intel imac, running snow leopard, backed up to a Time Capsule.

In order to create more space on my 500GB imac, I decided to use a Seagate hard drive (that has faithfully served me for backups over a couple of years via superduper, before time capsule) for storing my ever expanding home movie selection.

To avoid problems (and to make a clean start with this disk), I deleted everything on the Seagate drive via disk utility. I then ran a single partition on the drive using the settings of GUID partition with Mac OS Extended Journaled (i.e. so I selected partition so there is only 1 volume) . Everything went smoothly. I then copied my film collection to my hard drive. I then tested it - the films were on there and I could play them. So far so good.

Now when I reboot, I get the message "the disk you inserted was not readable by the computer. Initialize / ignore / eject"? The disk neither mounts on the desktop nor can I see it in finder. I cannot access any data on it.

What have I done wrong? Have I erased / formatted my backup drive incorrectly? How can I fix this?

I have another backup drive (that I keep offsite) that still is readable by the computer, so I do not think it is a hard ware problem.

I'm not in diaster zone yet. My movies are still on the imac, on time machine and backed up on the offiste external drive. However, in the need to create more space, I just need to be able to store files on external drives and then use them!!

Any help much appreciated

cheers
Paul