External Hard Drives slows machine to a crawl

I've got a 4 year old gateway running XP Pro. Recently the machine has slowed to a crawl. I've discovered that if I unplug my external hard drive (Seagate Model: ST900803FGA1E1-RK) the machine runs fine. I had been using the external drive without issue for months but lately it just criples the machine.
Any idea what I could do to troubleshoot this?
Thanks for your help,
Matt

 

Is the drive backed up if need be? Can you read and write data from/to the drive and are all the files that are supposed to be there actually there?

Usually its a sign the hard is malfunctioning. If you had another external HD or another system to try the suspect external on, you could eliminate USB port/Computer problem. You'd have to take the hard drive out of the enclosure and hook it up direct to eliminate the USB to SATA conversion curcuitry of the enclosure.

If it appears that it is the drive you could try testing the drive with something like SeaTools for Windows or purchasing and running SpinRite from grc.com.

 

Start with chkdsk /r on the drive. File system errors can slow things dramatically. The results will also show if any bad clusters were found.

 

If you can (or if it is already, great), be sure its backed up before /r. You'll probably be ok but I've seen that command orphan far too many otherwise intact files.