My side light ( driver side ) stops working sometimes?

Hello,
I have a renault clio 2.0 172bhp 02reg... There is a funny buzzing noise that comes from the side light on the driver side as i turn the key to the second click.
Sometimes both side lights work, infact i have no problem what so ever with the passenger side. but the driver side chooses to work when it wants to. It has been working fine for a good 4 months or so, and today it has stopped working.. the bulbs are XENON bulbs and were in when i purchased the car. The driver side has had a new bulb which was put in about 4 months ago. PLease any help or advise would be much appreciated.

Thanks ahead

baz
August 2009