Same problem here.

You have to disable wifi interface. This will unload kernel module I think. Deleting wifi interface will not help. Since than several days uptime @ 340Mhz.

So you can keep wifi network device but in menu Network->Wifi disable the device.

I think this has something to do with unattached wifi antena. I havent tried it but its possible that this problem will disappear with attached wifi antena even when not using wifi.