Headlight problem?

Hi,

I have the following problem that occurs every once and a while.

Passenger side headlight fails, after examiming the fuse it appears to be slightly oxidised, after cleaning it and replacing the fuse lights are ok for a while, then same happens again a few weeks later, could this be a bad earth ? if so how to test? also sometimes when I have the radio on and turn on the lights there is a slight interference on the radio.

The car is a basic nissan micra