Your computer does not enter a C3 state after you plug in and then unplug an external USB hub

After you plug an external universal serial bus (USB) hub into your Microsoft Windows XP-based computer, and then you unplug the USB hub, your computer may not be able to enter the C3 low-power idle state. To verify this problem, add the %C3 Time or the C3 Transitions/sec counter in Performance Monitor, and then plug in and unplug an external USB hub. In this scenario, the %C3 Time or the C3 Transitions/sec counter remains stuck at zero.

This problem occurs because the USB hub enters into a race condition that prevents the computer from entering the C3 low-power idle state.

To resolve this problem, obtain the latest service pack for Microsoft Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Microsoft Windows XP Service Pack 2.