If you keep getting this error message while connecting to your wireless network :"Windows was unable to find a certificate to log you on to the network NETWORK-NAME", there is one cause for your problem specially if your router keeps cutting down your internet until you reset, it's setting the encryption to WPA-RADIUS
instead of WPA-PSK on the client. The router and the client are both trying to find a RADIUS server with which to authenticate.
Since you don't have one, it complains using Microsoft technobabble.
Change the encryption to WPA-PSK (pre-shared key) on both ends.
If you can't fix this feel free to leave a comment and ask, please comment and tell me.