Radio interferes with I2C bus communication
2 k&Omega; should be low enough not to get much noise on the signal.  

But it looks like your problem lies somewhere else. It doesn't seem that the noise resets the controller. As long as the controller is functioning properly it should reset the watchdog timer so that it never times out to reset the controller. If the serial message isn't received properly your protocol should fix this. The reset is for emergencies, when the software goes bananas, or a power disturbance locks up the hardware. Letting the watchdog timeout because you're waiting for an ACK or a transmission restart is bad.