On a Windows Vista-based computer, the Smart Card Resource Manager may stop responding if a USB hub is disconnected from the computer while an application is communicating with a smart card reader
Consider the following scenario. You connect a USB Chip/Smart Card Interface Devices (CCID) smart card reader to a Windows Vista-based computer through an external USB hub. Then, the USB hub is disconnected from the computer while an application is communicating with the smart card reader. In this scenario, the Smart Card Resource Manager may stop responding (hang).
After the Smart Card Resource Manager stops responding, you cannot stop the Smart Card Resource Manager by using Task Manager. Additionally, you cannot access the smart card reader even if the USB hub is plugged into the computer again. In this case, you have to restart the computer.
Note: This problem does not occur if the smart card reader is directly connected to the computer.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB951373.