Ok, isso se resume a um bug na implementação da MFP da Cisco. Retirado da página de suporte da Microsoft :
The issue is due to Cisco’s MFP implementation. The Cisco reference for this issue is CSCua29504. There are 2 known resolutions for this issue:
Update the Controller to updated Firmware Image: Cisco has fixed the issue in an update release. You can download the updated software from https://supportforums.cisco.com/docs/DOC-27213. This option is highly recommended. This image has a fix for reporting correct “Key descriptor version” for M1 of 4 way handshake messages. 4 way handshakes complete successfully thus establishing a successful connection. This will resolve the connectivity issue described above and also allow you to use all Windows WLAN 8 features.
Roll Back to Pre-Windows 8 Drivers. Another option is to roll back to pre-Windows 8 drivers. These drivers can be obtained from the hardware manufacturer or their website.
Note that this approach will disable all Windows 8 specific WLAN features and user experience will be equivalent to capabilities supported by pre-Windows 8 drivers.
Existe também uma Página de suporte da Cisco para isso também. Posso confirmar que a atualização do firmware do ponto de acesso sem fio resolve o problema.