为何不断枚举？（给分）

  我在编一个USB键盘的驱动程序，通过USBVIEW可以看到USB接口的情况如下：
  Device Descriptor:
bcdUSB:             0x0110
bDeviceClass:         0x00
bDeviceSubClass:      0x00
bDeviceProtocol:      0x00
bMaxPacketSize0:      0x08 (8)
idVendor:           0x04C5 (Fujitsu Ltd.)
idProduct:          0x1020
bcdDevice:          0x0100
iManufacturer:        0x01
iProduct:             0x02
iSerialNumber:        0x00
bNumConfigurations:   0x01

ConnectionStatus: DeviceConnected
Current Config Value: 0x01
Device Bus Speed:     Full
Device Address:       0x03
Open Pipes:              2

Endpoint Descriptor:
bEndpointAddress:     0x81
Transfer Type:   Interrupt
wMaxPacketSize:     0x0008 (8)
bInterval:            0x0A

Endpoint Descriptor:
bEndpointAddress:     0x82
Transfer Type:   Interrupt
wMaxPacketSize:     0x0003 (3)
bInterval:            0x0A

我用DS编一个驱动以取代系统内置的，VID和PID都是对应的，且加了
两个单向输入的中断端点。
但是按装以后，系统在不停的枚举，用DS中的监控器看到的情况是：Usbqyp: In DriverEntry
-194.580696   Default     Usbqyp: m_bBreakOnEntry loaded from registry, resulting value: [0x00000000]
-194.580008   Default     Usbqyp: AddDevice called
-194.579618   Default     Usbqyp: Entering UsbqypDevice::UsbqypDevice (constructor)
-194.579512   Default     Usbqyp: Entering UsbqypDevice::DefaultPnp with IRP minor function=<unknown minor function>
-194.579319   Default     Usbqyp: Entering UsbqypDevice::DefaultPnp with IRP minor function=IRP_MN_QUERY_RESOURCE_REQUIREMENTS
-194.579213   Default     Usbqyp: Entering UsbqypDevice::DefaultPnp with IRP minor function=IRP_MN_FILTER_RESOURCE_REQUIREMENTS
-194.491259   Default     Usbqyp: Entering UsbqypDevice::OnStartDevice
-194.472256   Default     Usbqyp: Board did not accept configuration URB
-194.467799   Default     Usbqyp: Entering UsbqypDevice::OnRemoveDevice
-194.465200   Default     Usbqyp: Entering UsbqypDevice::~UsbqypDevice() (destructor)
-148.190592   Default     Usbqyp: In DriverEntry
-148.190505   Default     Usbqyp: m_bBreakOnEntry loaded from registry, resulting value: [0x00000000]
-148.189820   Default     Usbqyp: AddDevice called
-148.189554   Default     Usbqyp: Entering UsbqypDevice::UsbqypDevice (constructor)
-148.189453   Default     Usbqyp: Entering UsbqypDevice::DefaultPnp with IRP minor function=<unknown minor function>
-148.189253   Default     Usbqyp: Entering UsbqypDevice::DefaultPnp with IRP minor function=IRP_MN_QUERY_RESOURCE_REQUIREMENTS
-148.189144   Default     Usbqyp: Entering UsbqypDevice::DefaultPnp with IRP minor function=IRP_MN_FILTER_RESOURCE_REQUIREMENTS
-148.188656   Default     Usbqyp: Entering UsbqypDevice::OnStartDevice
-148.173355   Default     Usbqyp: Board did not accept configuration URB
-148.162322   Default     Usbqyp: Entering UsbqypDevice::OnRemoveDevice
-148.159305   Default     Usbqyp: Entering UsbqypDevice::~UsbqypDevice() (destructor)
不停的执行这个过程，为什么？