GoldenSilence, on 18 March 2013 - 11:13 PM, said:
Thanks everyone for your replies!
Turns out the bulb was faulty!

Thank god for failing electrics and shame on me for not being more rational!
We've changed the bulb now, hopefully no more black outs will occur!
Thank you for posting this !!!!!!
I wish you had waited a week or so. Just to see how many people told you you have a ghost, and to sprinkle salt, burn sage, etc,etc,etc....
It is nice to see a post like this, it shows how easily someone can think " paranormal ".
Glad it is fixed....