xilinx impact : usb failure

Hi groups,

I got a spartan3E starter kit and have experienced  trouble with usb
jtag interface.

While using Impact, usb cable can connect with my laptop, but not on my
desktop pc.

However pc usb port/controler seems ok : there are other devices
connected : wireless lan, external HD and CD/DVD recorder

checked numerous cables...

any clues,
regards


Connecting to cable (Usb Port - USB21).
Checking cable driver.
 Driver xusbdfwu.sys version: 1018 (1018).
 Driver windrvr6.sys version = 7.0.0.0. Max current requested during
enumeration is 280 mA.
Loopback test failed. Sent character = 10, Received character = 32.
Cable connection failed.