usb doesnt recognize the devices
 

the system is the folowing
winxp pro sp2
cpu 2.8Ghz
ram 1024 Mb

the system had no problem
the last days when i insert a usb device at the begining starts the
recognization and after appears a message tha the device is unknown

i try with many devices like usb hard disk, usb stick ecc

i deleted all the usb from control panel " in a safe mode" and i rebboted
but the problem insist

thnks