[CentOS] USB external HDD error messages

Hi - relatively inexperienced user here.  I installed CentOS 5.2 
yesterday (http install via a mirror, worked brilliantly), as well as a 
new Seagate 1Tb USB external HDD (from the new Xtreme line), for 
backup/media storage. 

Using fdisk I put two primary partitions on the Seagate, /dev/sde1 and 
/dev/sde2 (roughly half the drive each).  Then I used mkfs.ext3 on both 
to create ext3 filesystems on those partitions.  My fstab entries look 
like so:

/dev/sde1        /mnt/seagate1        ext3    rw,user,noexec    0 0
/dev/sde2        /mnt/seagate2        ext3    rw,user,noexec    0 0

I copied some data onto /dev/sde1 and went to bed.  This morning, I 
found a clump of kernel messages on the console (lightly edited from 
/var/log/messages):

kernel: end_request: I/O error, dev sde, sector 492896319
kernel: Buffer I/O error on device sde1, logical block 61612032
kernel: EXT3-fs error (device sde1): ext3_readdir: directory #30801921 
contains a hole at offset 0
kernel: Aborting journal on device sde1.
kernel: end_request: I/O error, dev sde, sector 12655
kernel: Buffer I/O error on device sde1, logical block 1574
kernel: lost page write due to I/O error on sde1
kernel: sd 3:0:0:0: Device not ready: <6>: Current: sense key: Not Ready
kernel:     Add. Sense: Logical unit not ready, initializing command 
required
kernel: end_request: I/O error, dev sde, sector 63
kernel: Buffer I/O error on device sde1, logical block 0
kernel: lost page write due to I/O error on sde1
kernel: ext3_abort called.
kernel: EXT3-fs error (device sde1): ext3_journal_start_sb: Detected 
aborted journal
kernel: Remounting filesystem read-only

I can guess that I/O means Input/Output, but other than that I'm 
flummoxed.  My fear is that the Seagate is defective.  Can someone point 
me in a good direction?  Any input would be greatly appreciated.