border collie obsessed with lights

Question
hi i have a border collie and she is 6 years old for as long as i can remember she has been obsessed with lights shinning on walls and floors especially if the light moves at speed. it is especially annoying when we are trying to eat our dinner and the light reflect off our knife and shines on the wall she goes mad and barks and growls, but she seems to enjoy it because her tail wags constantly. she is even worse if we get a torch out. is this normal for her breed. she is also snappy with children, but loves my 2 children to bits. when i walk her she snaps at other dogs when my boyfriend walks her she is fine.

Answer
Yes this is a fairly common problem in Border Collies-it's called 'Obsessive compulsive disorder' And is often treated with great success with medications such as prozac,but only  a vet can prescribe them

As for the aggression with children I think that would be best fixed by a trainer,there are trainers that deal with problems such as this-because they can see what the problem is and the best way to correct it