I would say this is related to trying to use WPA-RADIUS 802.1x authentication instead of WPA-PSK, so make sure WPA-PSK tkip is being used for wireless security.
Some blurb from google.
Windows Was Unable to Find a Certificate to Log You Onto
When trying to authenticate to the secure wireless network the user may see a pop up
dialog box stating:
Windows Was Unable to Find a Certificate to Log You Onto the Network
There could be a few reasons for this error.
• The user has not yet logged onto Entrust Entelligence™ Security Provider.
• When trying to access the certificate for authentication it cannot access the
certificate's private keys.
• The certificate it has been accessing has expired.
• No certificate exists for EAP-TLS authentication.
Check to make sure of the following:
• The user trying to authenticate is logged into Entrust Entelligence™ Security
Provider before trying to authenticate to the secure wireless network.
• The validity period of the certificate being used is valid.
• The user's certificate exists in the Current User certificate store, and meets the
criteria outlined earlier for authentication with EAP-TLS.