Redhat linux enterprise server 5.0

sir, I had recently installed Redhat Enterprise Server 5.0 on Intel Core Duo 1.8 GHz / Intel 946 / 2.00 GB DDR -2 RAM / 160 GB HDD .
i am faqcing some problem while detecting Seagate External USB Hard Disk Drive, when i connect throu USB port its not detecting the USB HArd Disk but when i connect other USB Device like Pen Drive, USB Camera/ USB Keykoard+ Moouse or USB Mobile phone,Handycam its working fime on the same port.
i also installed windows xp on the same system and it supports USB Hard Disk on the same port.
so please provide me some help about the same problem, i will be very kind to you sir.
Thanking you,

Rajesh Yadav