JSI Tip 7850. Windows XP does not enter a C3 state after you plug and unplug an external USB hub?

When you plug an external USB hub into your Windows XP computer, and then unplug the USB hub, your computer may not be able to enter the low-power idle state (C3).

To determine if your computer is effected:

1. Add the %C3 Time or C3 Transitions/sec counter into Performance Monitor.

2. Plug in an external USB hub.

3. Unplug the external USB hub.

4. If the %C3 Time or C3 Transitions/sec counter remains stuck at zero (0), you have this problem.

NOTE: This problem is the result of the USB hub entering a race condition that prevents your computer from entering the C3 state. There is currently no fix, but hopefully the next service pack will address this issue.