[ntdev]Ask for device driver again in Win2k

Hi,

I am developing a win2k driver for a USB product.

After the first time my USB adapter is inserted and driver is installed form
a floppy disk successfully, if this adapter is removed and another adapter
with a different serial number is inserted, most of the time, the system
just displays some information about finding a new device and loads the
driver automatically. But sometimes, the system asks for the floppy
installation disk again. Does any body know why?

Thanks in advance.

James