Vista - USB Device not recognized

Hi,
I have been getting the error messages "USB device not recognized"
from Windows Vista. It keeps on repeating itself at sporadically. The
problem is that I do not have any USB device attach or plug to my
computer. I happens to sometimes plugged my USB Flash key device to
drop some documents on my hard drive but I immediately unplugged the
device after the task is done.

I used to have a Lexmark 1290 printer plug to my computer but since it
was not working fine on Vista I have decided to unplug it and delete
the peripheral in my printer manager.

I have installed the latest Windows Vista Update, BIOS update, and all
possible drivers but I still having the messages.

Here are the specs of my computer:

Motherboard : EVGA 680i nForce
VideoCard : EVGA 7900
HDD : Seagate 320 GB X2 (one with Vista main hard drive and one with
XP)
Memory : 2 GB OCZ dual memory

Does anyone have a idea of what could be my problem?

Thanks