How do I get rid of a warning light?

I have a 52 reg vectra (diesel) and when I first turn on the engine a car symbol with a spanner through it comes on and after about a minute on two it goes out, the car runs perfect and its only the first start up of the day and also when I finish work at the end of the day that it does this.
The car manual says its an electronic fault symbol but also says that if if come on and goes out again it is of no significance. What can I do to get rid of it?