This issue can be caused by an Interrupt Request (IRQ) conflict or a firmware issue.
1. Uninstall the current verison of Client Utility and reinstall the Latest ACU or ADU client utility.
2.Also try to upgrade the firmware and the driver version.
For information on IRQ conflicts, refer to the Resolving Resource Conflicts section of Troubleshooting Cisco Aironet Wireless LAN Client Adapters.
WLAN adapters (wireless card) / ACU (Aironet Client Utility)